Why do you perform without a contract?

With the recent interest been shown in reggae music, UK artist and musicians are seeing an increase in the amount of live work available to them. Unfortunately the rise in UK reggae's popularity has also brought a rise in complaints about bad promoters. Whilst listening to artists complain about cancelled shows and being short changed at the end of a gig etc., when I ask the simple question about what was agreed in the contract, I'm surprised to learn that most of them did not sign a contract!

Why does the UK reggae scene continue to operate like this, how on earth can standards improve without basic good business practice being adopted?