Most employers are aware of how business engagements work.

And the reason you see "starter-level" next to important jobs is that most employers are aware ...

that starters don't have a clue.

I would always give at least two weeks notice, and in one case interview my replacement. So while it may have been a shock, they always had time to adjust, and I didn't leave loose ends.

They still have the power and the money to employ other people.

Which is a different situation that needing to be employed to put food on the table.

To put this in a slightly different perspective. Let's say you had hired a babysitter so you could go out for the evening. At the last minute, the babysitter cancels, and it is too late to get another one. Now you are either scrambling (calling relatives, etc) or you cancel your evening plans. Now let's add to this that your kids really like this particular babysitter, who has quit the babysitting business permanently, and it takes a bit of trial and error to find a replacement that will work for your kids.

So an employee leaving does have some impact. On the employee side, of course there is the food-on-the-table issue, which can be important if there isn't a safety net. Which is why it is critical to live within 75% of your paycheck, so that every year you can survive 3 months unemployment.

>Which is why it is critical to live within 75% of your paycheck, so that every year you can survive 3 months unemployment.

And then you get sudden medical bills or more months unemployment or some other sudden expense :-(

But if you're not living paycheck to paycheck, unexpected expense are easier to survive.