Because in my opinion, I think its crazy having so many 'rules' for the customer to agree to.
I'm not knocking the way you do it, I salute you, providing you get each customer to actually stick to these rules.
I guess if you make customers aware of your T+C's right from day 1, then it would be easier than for example me now trying to get my 500+ customers to agree to something like yours.
You must have turned up to quote a new job, to then be told to clear off after they have read your conditions surely?