Whether a job is a 'liability' or not is also a question to the laws, many of which are also designed to destroy competition to the larger players in the field, those who donate money to the politicians. However checking oil and tire pressure and wiping your windshield and pumping your gas is a courtesy that can no longer be provided to you by the gas station, not because of liability, but because of the all the labour laws and inflation and government is the responsible party for all of it.
It doesn't cost that much to add them to a busy station if you only account for wages and typical overhead
- you obviously are not running a gas station or any business for that matter, so you should really abstain from making ridiculous statements about what a cost is to hire somebody. The cost to hire somebody today in USA is much more than just the wage itself, an employee cost to business is easily twice their wage if not more given the laws and taxes and liability for all the nonsensical government discrimination laws, etc.
The benefit to the business has to be tangible, it has to cover the cost of having that employee working there and it has to provide something on top, the profit has to be material. If you get more customers than your competition by providing better service that is a material benefit as long as you can measure it. On the other hand given the tiny margins that gas stations live on, it is clearly impossible to hire attendants to check your tire pressure and oil and wipe the windshield and pump your gas, in fact most if not all gas stations are now manned by one person.
One person where it wasn't uncommon to have 4-5 people before all the laws and inflation destroyed all those opportunities and automation was increased and customers were switched to the self-serve model.
Given the higher minimum wage laws (most of which didn't kick in yet, by the way, so the effects are not there yet), there will be more automation done in places where people used to provide the service. You will not have a waiter, you will have fewer clerks, you will not have somebody answering phones.
You'll bring your own food to the table, you'll use a self serve cash register, you'll talk to an answering machine (well, at least off-shore call centres mitigate this problem somewhat, people like talking to people on the phones, not to machines.)