[mgontav]

This was pretty much my experience as well: had to build a small scraper 2 years ago to alert me whenever spots for camping became available in Yosemite. Bear in mind that this was around 3-4 months in advance. Just for the sake of it I let it run after we had the spots, to understand how many people cancelled, and the amount of cancellations are actually insane.

While I don't think my approach was too harsh (I wasn't constantly querying nor booking automatically), it could be solved if they provided their own alert system, or discourage the book-cancel behaviour (higher cancel fees? Might not make much sense since the camping itself is pretty cheap...)