I work in Procurement and run RFP's all the time. you are right that enterprises go through this whole process and that they ask a lot of questions about software capabilities. But honestly, at the end of the day, the process is so long and drawn out mostly because of compliance. Start-ups are fun companies that don't really have to worry about the threat of being regulated or audited by the government. But a publicly traded company that has a lot of risks (banks, car manufacturers, enterprise hardware) is going to be constantly under watch. As soon as the government finds what it deems a mis-use of funds, say sainara to productivity and hello to deep auditing and a halt on productivity thanks to long meetings with auditors.

I really think if it was about price and quality, you could get through a sourcing effort in a week or two. Show me what ya got, tell me how much you are charging.

Full Disclosure: I hate my job.