Serious question: in that world, who cleans the toilets?
These aren't gig jobs. They offer steady employment with predictable hours and wages. If everyone has a basic job contract (which is a right in some countries already), it is even more predictable. If the job itself isn't good enough for your basic economic needs, the safety net kicks in. If they lose their job, the safety net kicks in so they aren't struggling to get by with gigs. (Obviously idealized situation).
The point is that worker never is forced to piece together gigs to be able to pay for food, clothing, shelter, and other things society sees necessary to be a full citizen. The same employee might decide to save for a house, vacation, buy a newer vehicle, or something similar and then work gigs on top of his normal employment. It isn't that everyone will be paid well or that no one will clean toilets, but it may mean that companies like Uber would have to hire regular employees so they have the same sort of economic security as the janitor would.
That world would have more to do with a Star Trek episode than with the current society.
Isn't the point of an imagined scenario not to be like current society in some way?
There are about 1.9 billion acres of land in the continental united states. That works out to 5.8 acres per person. If people could afford to purchase 100 acres of land per year, and even a tiny percent of people utilized this - land prices would skyrocket. And a similar story would end up being true of other resources and labor costs.
In describing fantasy scenarios you have to consider the implications on the allocation of limited resources such that everything isn't just completely overwritten by inflation.
While land is limited, wealth and capital are not. It's perfectly possible to posit a society where people own, say, shares of robotic mining companies that roam the solar system for resources. Or that values genuine human sexual intercourse to the tune of one million dollars per act, inflation adjusted. It's much harder to substantiate how such a society would actually look like.
The first would be where janitors would go and retail is another poorly paid job today.
The average house cost in 1960 [2] was $11,900.
So with a house price of around two times yearly income, we get to about $100k wage for a janitor or retail clerk in 1960. US post WWII was a pretty unique situation, but one would hope that you should be able to more than imagine such a situation. You can study the existence of such a culture in the recent past and still talk to people who actually lived it.
[1](https://babel.hathitrust.org/cgi/pt?id=mdp.39015021301612;vi...)
[2]https://www.census.gov/hhes/www/housing/census/historic/valu...
An inflation adjusted wage of $5000 in 1960 represents $42.500 in 2018, which is in line with the often repeated tidbit that real wages of blue collar workers have stagnated for decades.
Therefore, what you are describing is a world with similar real wages to those of today, and with real estate cheaper by a factor 2-3x, inflation and quality adjusted. That is indeed easy to imagine.
What I am describing is a world where real wages are 4-5 times larger. Yes, those wealth increases could be trapped by a ballooning real estate market, where a single bedroom semi is worth $2 million at current purchasing parity, making it very similar to your world. Or something else could happen entirely, that is almost impossible to predict.