In my experience there are sites and there are proper constrcution sites. Site is a term used to describe most places of work for a trademan but a construction site in my opinion is a larger set up and any construction site will be operated under a main contractor who will have the relevant policies in place. I have always had to produce a CSCS card on any construction site that I have been on in the last 4 or 5 years.
It has only been smaller jobs such as a single newbuild or renovations etc that I have not been asked for one. If you go on a building site run by any of the big boys e.g barrets, taylor woodrow or even the likes of interserve etc you will always need a CSCS card.
I have seen a few tradesmen get on site with the basic card though.
Unfortunatly as a self employed tradesman, anyone who is self employed needs to invest in themselves to get on things. I honestly believe that spending thye cash and getting certified in areas will set you ahead of many people, it will also get you access to site or wherever else you need to go.
In the last few years I have invested in myself and itr has paid of, SVQ, NVQ, CSCS, IPAF, PASMA etc etc. The more you do, the more you get.
If we want things we need to work (or pay) to get them. I do think its a bit odd that we need to pay for the test and then the card. There shoud be one fee in my opinion.