[scott_s]

Government officials are not a part of the market economy.

It's paying for service, it just goes through unofficial channels. I live in a small college town. I eat at the same vegetarian restaurant for lunch almost every single weekday. I sit at the counter with a book, and make small talk with the cooks and servers as appropriate. I unquestionably receive preferential treatment from them. The cooks sometimes slide me extra food if it's not enough to sell as a full meal, or if someone sends back food that's fine to eat. The servers take my order almost the moment I take a seat at the counter and it's usually served the moment it's ready.

I don't tip extravagantly ($2 for an $8 meal), but I'm friendly, easy to serve and they know they'll see me every day. I get preferential treatment, but I'm also giving them preferential treatment by coming in every day.

You have a right to be treated the same as everyone else by the government. You have no such right at a service establishment - yes, they cannot refuse service for the all of the standard prejudices. But they most certainly can offer a higher level of service to people who pay more.

[willyt]

OK, what about if you employed someone to tender contracts for you and one of the tenderers took this person out for an extravagant lunch in the expectation of influencing the bidding process? Wouldn't that be immoral?

[scott_s]

I would think so, yes. But restaurants, bars, massage parlors, etc. are service-oriented places where tipping is already the norm. The precedent for more-money-means-better-service has already been set.

[dedward]

No - it would be a gamble. Immoral, and possibly a fireable offence, would be if your employee actually gave them a better deal in exchange for the kickback - in which case you, as their employer, can deal with them as you see fit.