This all true, and empowering for those who have the relevant know-how and opportunities. However, these apparent efficiencies are built on the back of the factors that GP points out. Empowerment for some relies on structures that disempower others. Agency staff live precariously; the companies that use them have ever tighter margins, they are increasingly hollow shells that serve only to generate cash not to provide the security of employment.
The convenience we appear to benefit from is an ever-thinner veneer that disguises deeper problems.
I've seen many guides to doing this in the form of blogs. This is not hard information to come by.
There's also an implication that it's simply okay to let job security rot away, that people in precarious work should simply read a few blogs and retrain. I'm not convinced that it's a good plan to ignore creepingly pervasive employment insecurity.
I remember when I wanted to sell in France, I had to find a French distributor, make a French version of the product, guess how many would sell there, ship a pile to the distributor, the distributor collects most of the money, and unsold merchandise is scrapped. If I didn't have a distributor, the merchandise was always getting hung up in customs, would disappear in the mail, would take 6 weeks to deliver, I'd get paid in dollary-doos that no bank would exchange, etc.
Rinse, repeat for every country.
Today, I ship all over the world via the internet for $0, have no stock, no scrap, no middlemen, get paid instantly, ship instantly, and the transaction cost is 1% for paypal and 3% for credit cards.
Still have to pay taxes, though :-)