He is referring specifically to land, which he rightly viewed apart from all other, more natural forms of private property.
In fact the only tax that I saw him advocate for raising is ground rents, which is exactly what geolibertarians advocate. Land taxes are also the only tax that economists believe cause zero economic inefficiency.
"The subjects of every state ought to contribute towards the support of the government, as nearly as possible, in proportion to their respective abilities; that is, in proportion to the revenue which they respectively enjoy under the protection of the state."
Income from overseas investments wouldn't be under the protection of the state where they reside, and appropriately, wouldn't be taxed by the state in which they reside.
On the subject of taxation, almost all of his admonishments were to tax less and less intrusively:
To subject every private family to the odious visits and examination of the tax-gatherers ... would be altogether inconsistent with liberty.
and
“[Governments are] ...without exception, the greatest spendthrifts in the society.”
and
“The agents of [government] regard the wealth of their master as inexhaustible; are careless at what price they buy … at what price they sell.”
and
“Those unproductive hands [in the government] … may consume so great a share … that all the frugality and good conduct of individuals may not be able to compensate … this violent and forced encroachment [of taxation].”
and
Now many such things may be done without intitling the people to rise in arms. A gross, flagrant, and palpable abuse no doubt will do it, as if they should be required to pay a tax equal to half or third of their substance.
and
Little else is requisite to carry a state to the highest degree of opulence from the lowest barbarism but peace, easy taxes, and a tolerable administration of justice: all the rest being brought about by the natural course of things.
and
There is no art which one government sooner learns of another than that of draining money from the pockets of the people.
and
“The profusion of government … [has] retarded the natural progress.”
and
The statesman who should attempt to direct private people in what manner they ought to employ their capitals, would not only load himself with a most unnecessary attention, but assume an authority which could safely be trusted, not only to no single person, but to no council or senate whatever, and which would nowhere be so dangerous as in the hands of a man who had folly and presumption enough to fancy himself fit to exercise it.
His preference for ground rents:
Both ground- rents and the ordinary rent of land are a species of revenue which the owner, in many cases, enjoys without any care or attention of his own. The annual produce of the land and labour of the society, the real wealth and revenue of the great body of the people, might be the same after such a tax as before. Ground-rents, and the ordinary rent of land are, therefore, perhaps the species of revenue which can best bear to have a peculiar tax imposed upon them.
Him supporting revenue taxation would totally conflict with a sentiment like this which he expressed:
To subject every private family to the odious visits and examination of the tax-gatherers ... would be altogether inconsistent with liberty.
The visits are now replaced with the onerous requirement to keep records of all private financial transactions one engages in all year, and produce them on demand if the taxing authority should request them, and to detail to the taxing authority all the income one has earned from any private trade, even barter, and hand over a sizeable share of the value received in the totality of that trade.
An income tax did not exist in Smith's time, and had it been proposed in that period, it's extremely unlikely he would have favored it given 1. his admonishments against expansive government that intrudes upon the private lives of citizens, and 2. the need for an expansive tax enforcement apparatus, that invades the inner sanctums of the private lives of citizens, to enforce an income tax.
"Scab" is the union slur for poor unemployed people.
"Scabbing" is a pejorative term, that has been used to dehumanize replacement workers and incite assault and murder against them.
The answer here is twofold: First because the state exists and will enforce property rights, protecting scabbing and preventing sabotage with force, if not escalating to outright war as they did in the early 1900s (continuing into the 70s in Kentucky.) Second, a capitalist can live just fine with a closed factory whereas workers will not be able to survive without work.
In any case, I encourage people to actually read Adam Smith for themselves. You can not only refine the mental model you have of economics but also learn that the popular Adam Smith that is caricatured is not the one who wrote Wealth of Nations. Did you know, for example, that the "invisible hand" is mentioned only once in all of WON? On the other hand, actual market mechanics and state policy (some of which was later discovered to be wrong) were discussed in great detail. You can find a lot of fun quotes too:
"As soon as the land of any country has all become private property, the landlords, like all other men, love to reap where they never sowed, and demand a rent even for its natural produce." [1]
1. From "CHAPTER VI. OF THE COMPONENT PART OF THE PRICE OF COMMODITIES." https://www.gutenberg.org/files/3300/3300-0.txt