Of course you can't make that kind of "promise", which is what Pyles alleges coaches are telling him is going on. Good luck to those coaches, Pyles or anyone else trying to prove such a thing.
A quid pro quo really only becomes a type of bribe when there is a clearly identifiable exchange of property based on an explicit promise.
If anything going on the difficult issue is knowing where to look because the NCAA can’t be looking everywhere. But to the is it identifiable:
Let’s say top recruit A gets a full (use 100% to keep the math simple) ride offer from the coach at Univ X and accepts. A few/several months late X gets back to A to indicate we need to reduce the offer to 50% (could be they find they can go after top recruit B, or they’ve got a guy who wants to redshirt/stay around another year etc.) but we will make up the 50% once on campus and in the program from over here. Now all may be fine as long as A goes to X, but what if A decides nay I don’t trust them I’m now going to Univ Q and of course there might just be some discussion at some point in time regarding why A went to Q over X.
Well if knowing where to look (enough As to connect some dots) there’d be records of initial offer %, changes to the % and tax etc records coming from the here and to A.
Now add the RTCs to the equations and there’s more here to add to the shell game and perhaps raise it to an even higher level and perhaps there’s a new Univ Y that is now playing the game at said higher level. But let’s say you are X, you don’t really want to talk about it (what Y may be doing), so do you just join the new shell game?
There can be an explicit promise and the documentation to identify the exchange of such property. Thing with the NCAA is they don’t necessarily have to have all the dots hard connected, just enough info to know there’s a lot of smoke.
Of course this is all just a hypothetical example. ;)