Knowing almost nothing about the product other than a quick browse on the webpage, I'd say 42,300 sats per month equals 42,300 pretty good reasons. 😉 There are some months that a very small or startup business may not even get that much in sales! Someone selling stickers for 1000 sats a piece? Or what only selling an occasional piece of artwork? There are a lot of usecases that a monthly sub just won't work.

Seems like a decent product, but really running @btcpayserver is so easy, why not go fully self-sovereign route? No processing fees, no subscription fees and when your product takes off and you're pulling in 5M sats a month then you can zap the devs 69,000 sats/mo. 🤙
 https://image.nostr.build/abec9fe0578d71464c748933ab576e3a54d72c17b95f44e3e0cf77f1b733b3b3.png