The US is a different country to the UK, with different ways of doing things. I don't think it's reasonable for British people to say they 'should' do things a different way because that's what we do.
As far as I can tell from talking to Americans one of the main ideas of life there is that a person has the right to try to improve his or her lot by his or her own efforts, with minimal interference from the State. You see this in the way that taxes are not shown as part of the price of items, but added when you come to pay, so that it is clear to everyone how much is taken by the government.
Waiting staff are employed by the restaurant to be available to serve the customer, but the customer is expected to pay for the actual service. This gives the staff the opportunity to 'do a better job' and, hopefully, get paid better. I've heard British people complain about how intrusive they find waiters in the US, but the waiting staff I've spoken to say this is because they are trying to do a good job, as seen by US customers, who may expect more attentive service than British people often do.
It's the same situation with taxi drivers, bell hops, etc, etc. It's a different way of doing things born from a country with a pioneering, get-on-and-work-your-way-to-sucess history.