Gratuities - I think I've changed my mind

Anyone who has read my blogs before will know that I’ve always been pretty against tipping when it’s been made compulsory. It’s not that I’m tight, (honestly), I just begrudge having to pre pay for a service that I haven’t received yet.

It’s also always irritated me that society only deems certain occupations as ‘tip worthy’.
Why should I tip my taxi driver but not my bus driver?
Why tip my waiter in a nice restaurant but not the serving staff of McDonalds?