Scarpe, please note that there is a difference between Canada/USA/UK/Europe and countries with lower costs of living. Paying someone $25 when they are trustworthy enough not to steal from you is worth it when minimum wage is 8 bucks/hr. If minimum wage is <$2? Maybe not.
Likewise, a construction grunt easily makes twice to 2.5x minimum wage after a few months. Of course, that could be an artifact of Vancouver's currently obscene real estate market. You clearly are out of touch with how North America works...
And lastly, its not an issue of "how much they know" or "how hard they work"; its an issue of "what is their job worth". I HATE tidying up. I think $100 a week would be a reasonable sum to not have to do much of the asinine cleaning - like washing windows/dusting/ etc. Likewise, if you're a contractor earning ~$1+K/day, paying out $25 in wages to attract decent workers makes sense.
As for servers? Estimate that 20% of your bill is going to making your night go smoothly, and is just how things work. I'm willing to spend 20% of what my meal is ticketed at to pay for good service.