These services wouldn't exist without someone footing the bill so yes, for the vast majority of attendees, their money is "footing the bill". But they can and do provide a service. How much your son gets from this service is up to him. If he's got top 10% metrics then it's at least the 3rd-party validation of those metrics that is the service. You will find many differing opinions on this site but it doesn't take a rocket scientist to see which one of the services is at the top of the chain. Yes, they have great marketing but more importantly they have a lot of credibility and even better data services. So, for what it's worth, when you think your son is top 10% here is my ranking:
1. Perfect Game (PG)
2. Prep Baseball Report (PBR)
3. Baseball Factory (BF)
Both PG and BF run showcases nationally in a standard format--this is because they are Nationally-run organizations. PBR, on the other hand, is a National organization made up of local franchises. Their showcases can differ by quite a bit. I'm not saying that is necessarily a bad thing--it's just that results can vary. As an example, during my son's recruiting journey we found that PBR collected exit velocity sometimes during BP and others off a tee. They also did not distinguish between wood bat and metal bat exit velo's. I believe this to be the case with BF as well. BF also records positional throwing velocity by having players run-and-gun into a net--no difference between MIF, CIF, OF and catchers. In my opinion, recording positional velocity this way is no way near as accurate. PG, on the other hand, runs their showcases the same way regardless of the location. The metrics they collect are about as standardized as a service can get and they have collected these metrics for almost two decades. Most importantly, you can view these on their website regardless of when and where, and who. This is how they are able to use metrics to help with their assessments. While some may think their assessments are terrible, you cannot argue they do not have the best metrics repository in the business.
PG is more expensive, of course, but they do include a games portion to their showcases and a lot of that cost goes toward umpires and evaluators at each game. While PBR may now have some events where games are played they are not part of the usual showcase events. BF does not play games.
Yes, as adbono points out, weather can be a factor so perhaps choosing which showcase you attend can help in this regard (like attending showcases in FL or CA). That being said, the event his son attended in 2016 did have 2 OF's throw 90+ (and an additional 9 threw 85+) and 2 players ran sub-6.6 (another 16 ran sub-8.0). Of course I can easily pull these metrics because PG has this data! You can go on and see which attendees of that event eventually committed to a college (not saying this event had anything to do with it) and what other events these players attended whether they improved their metrics over time.
Yes, the PBR Futures Games is a great event but generally you have to have attended a PBR showcase somewhere to get an invite. Just like the PG Junior National and the PG National. I'm not saying there have never been players invited to these events without first attending but I'm sure that number is very, very low.
And BF? This org really is a money grab (except for the metrics collection) and is used as a tool to get you to attend their other events. No, I don't mean a generic email inviting you to attend another event but an honest-to-goodness salesman who calls YOU (the parent) on the phone to "discuss" your players results before inviting you to another event which happens to cost several thousand $'s.
Of course I am leaving out a lot of other organizations--like academic oriented Showball and Headfirst, USA Baseball (and all the little qualifiers leading up to an invite to a regional and national event), and of course Bob's Area Code games. The three I list and discuss above are the "mainstream" prep metrics-collectors.