First, you need to distinguish between showcases vs. tournaments where numbers are recorded. Then you need to distinguish between players who are D1 no-doubters vs. players on the fringe. Some of the people who have posted here have P5 players, their experiences are very different from players who are throwing 80 mph as sophomores.
In our state (and I think many), PBR serves both as a data-collecting service through its showcases, and also as a regional scouting service. PBR identifies top players, whether or not they do their showcases; they also publish data about anyone who pays for a showcase. These are not necessarily the same thing! So, it's not surprising to me that you see many non-D1 showcase participants. On the other hand, PBR's Futures Games (with teams selected by the state PBR) are a high-level recruiting showcase tournament.
If you have high-level skills and show up at a random showcase, you will see results. If you don't, your showcase fees are paying for the scouting of others. See this post from the founder of PG, which includes, "If your son has talent you will be very happy you attended. If your son lacks talent, you will be throwing your money out the window.": https://community.hsbaseballwe...035#9740668003950035.
To get recruited, a college coach has to become interested. How does this happen? Could be the player sends an email with metrics (verified with PBR or PG) and link to video. Could be because summer/travel coach tells the college coach about you. Could be from seeing a player play, either in a tournament or at a showcase, or at their camp. If you go to a showcase with coaches present (e.g. Headfirst, some PBRs) then they will see you and get all your numbers. If you only play in a tournament, they may look your numbers up on PG or PBR. If you only do showcases with no coaches watching, your numbers will be available to verify what you or your travel coach says.