You should read a few call-for-proposals, it's pretty enlightening. What I learned (hopefully this differs from place to place) is that they write them in such

You should read a few call-for-proposals, it's pretty enlightening. What I learned (hopefully this differs from place to place) is that they write them in such a way that only huge, dishonest shops can respond, by making the requirements huge and contradictory. An honest shop can't call out the contradictions and get the work because "fully satisfying" the requirements is necessary to be accepted. A small shop can't afford the time and expense to respond with a proposal. In both cases you need to build in enough overhead to cover the countless hours spent arguing about the featureset and to afford the lawyers when the litigation comes a few years down the road. I don't think the government means to lock out small vendors. It's just that bureaucracy tends to generate bloated and inefficient systems like this, in which the only part of the contract the vendor can afford to skimp on is the implementation itself (and not the lawyers, negotiators, managers, etc.) The people who work for the government want good, working systems, they're just prevented from choosing vendors who can produce them because using common sense is not sufficiently bureaucratic.