First, the modules never became one product. The sales tool doesn't really know what billing knows; cancellations go through while drafts continue; door fobs keep working after memberships end. Staff bridge the seams by hand, every shift.
Second, the business model is the payment flow. The platform becomes the merchant of record, drafts your members in its own name, and earns on collections, late fees, and recovery. Your members' statements say the platform's name, and when billing goes wrong, your gym eats the reputation damage.
Third, pricing is quote-based and the contracts run years. Nobody publishes a number because the number depends on what you'll accept.
The clearest way to see all three at once is to try changing who holds a family membership. A couple separates, or a spouse takes over the payments. On most platforms the answer is to cancel the account and build a new one, which resets the join date, throws away the check-in history, and usually double-bills across the seam. Then the fob keeps working anyway, because access lives in a different module that did not hear about it.
In Plexon that is one action. The holder changes, the payment method and any balance move with it, door access updates in the same transaction, and the authorisation gets signed on a tablet at the counter and filed against the change itself. The membership keeps its age. Nobody re-types anything.