Good point. Makes you wonder doesn't it.
But totally nothing to do with an online service, providing listings.
At the end of the day we have to accept that this is largely a hobbiest industry and not one taken seriously or moderated by official standards.
This service provides leads for most of these opperators and the higher (much smaller) end is better sourcing their work elsewhere.
Spend what ever it is we spend on NAD on some Google Adwords or something. It will continue to do well off DJ's who want to get some money for their summer holiday or Christmas presents or are just simply working on a loss.