alt Hacker NewsEconomics has this concept called revealed preferences[1]. These are preferences that people don't say that they want, but is what they actually use preferentially. An example of this the ordering machines that you normally now see in fast food places these days. People often say that they'd rather order by a cashier, but when given the choice of using one of these machines, or waiting a few minutes in line to get a cashier, they overwhelmingly choose for the automated option.
Tying this back to your first point, the revealed preference is that people would rather fill their own gas tank, rather than be forced to wait for someone to come and fill it for them.
Bagging groceries is different, however the revealed preference is that people would prefer the lower price/lower service supermarket, and those that need the help have to ask for it.
You are correct that everyone needs to earn a living, I think that most people would prefer that others can earn a living doing a somewhat meaningful job, in a somewhat safe manner.
The reason that much of this isn't automated has nothing to do with ensuring that jobs exist, but rather that the cost of automation is higher than the cost of labour. This is what op is talking about.
> the revealed preference is that people would rather fill their own gas tank
MOST people, not ALL. Smaller markets can still be profitable and useful markets. Most people prefer to pay less and cook their own food, but some people prefer to pay more and have lunch delivered to them. That market is doing quite well despite the fact that pretty much everybody can just stick something in the microwave. There are endless more examples.
> doing a somewhat meaningful job
Who decides what's "meaningful" and what isn't?
> The reason that much of this isn't automated has nothing to do with ensuring that jobs exist, but rather that the cost of automation is higher than the cost of labour.
SOME of the times, you're right, but not ALL of the times. People (most often via unions) aren't resisting automation because they're excited about moving to a "more meaningful job" or because they hate progress. They're resisting because in modern society they MUST have a job, and if they spent the past two decades working as cashiers in supermarkets, their ability to find "more meaningful jobs" at this stage in their lives is extremely limited, and chances are they're gonna have to take a pay cut. Progress cannot come with higher unemployment and poverty rates. If that means low income, less meaningful jobs remain, so be it.