Well I have been in the industry for over 30 years and I would say most RFP's come out of organisations who have a predisposed point of view on the technology they will likely buy, but not all of them. My advice from over 30 years in the game is ignore the ones you didn't expect. You are likely making up the numbers in such situations, even if you are told "we really want you to respond", which typically means "we need to have a response from you" which is not the same as "you stand a chance'. The ones I have won I have usually known I am well placed because I have been aware of the companies ambitions, engaged at the top level and prepared well in advance of the documents coming out, sometimes months and even years ahead on major projects. Doesn't mean you win them all as you can still not be best fit but in the same way you can still win ones you are not favoured for. I have worked across public and private sector in that time and you know when a vendor has helped as usually there are reference points that use that vendors language.
Industry is full of corruption, it is naive to think otherwise sadly. Sometimes you find it and can act against it. In the years gone by I have actually seen a head of procurement fired for underhand activity but most RFP's will clearly state we don't have to pick the best one, the cheapest one, the one we should etc. etc. etc. You can win the process and lose the deal. I have also rejected RFP's from companies I feel are doing it wrong and in doing so got them to revise the whole process. Nothing better than saying "sorry, this is a terrible approach and I can't justify responding". Takes nuts but why consume a term of people on a war you never stand the chance of winning.