On my last trip to Cuba, I talked to a local photographer for an hour and he said he has to work under the table as much as he can or the government takes most of his money(communism?) Basically, their government can't allow photographers make $400-500/wedding, while others make that amount in a year. Chances are, you shouldn't try to persuade them to do it under the table. Their communication lines are being watched(according to him),so if anything, they usually are more willing to negotiate in person. Still,their camera equipment suffers quite a bit. The cameras he showed me were so old and rusty, it was painful to watch. If it breaks, it can take up to 8 months to get it fixed, as they have to send/receive it through someone else.
Cuba is still one of the happiest countries on the planet!!