alt Hacker NewsIt's weird how you both describe visiting other cultures AND thinking everybody's just like you in the same paragraph.
1. You can fill your own car with gas, but some people can't, or prefer someone more knowledgeable to do it for them. Some people like the comfort of having someone bag their groceries for them, or have disabilities that necessitate it. Some people are old. Today you learned.
2. Your economic system is not different than theirs. Everybody NEEDS a job to support themselves, their families and to be functioning members of society. That means jobs that can easily be automated won't be automated. Also, you may make a lot more money than that kid bagging groceries to make a few bucks for himself, but at least what he does actually helps someone. What we here on Hacker News do is mostly build imaginary products that will be gone and forgotten quicker than you can say "Al Bundy".
3. Not only that, all of us here have basically written our own replacements and made ourselves obsolete. Something tells me your job isn't really needed too.
Economics 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.
[1] https://en.wikipedia.org/wiki/Revealed_preference