We’ve been to a number of camps with our 2020 (HeadFirst, Showball, Stanford, Princeton among others) and we’ve made a few observations about schools recruiting catchers. For example, at Princeton and Georgetown our 2020 was told that their starting catchers were both walk ons which seems to suggest that this isn’t uncommon.
Walk-ons happen. But coaches do not rely on walk-ons to earn playing time or become contributors. An injury or two happen or the kid makes the team as a freshman walk-on and is ready to start by the time he's a junior senior is most likely the norm for a walk on starter. You also mentioned two schools that offer no baseball money and very little (if any) baseball money. Technically speaking, they're all walk-ons. It's much easier to do this at a school where baseball money is scarce or non existent. At a fully funded school 23-27 guys will be on scholarship with another 8-10 walk-ons. Who are usually recruited guys who just aren't receiving money or in guys who qualify for enough academic money or are in state so they don't necessarily need baseball money. Even more so at the catcher position where you need to recruit somebody. If a walk-on happens to out play them then so be it but definitely the exception.