I would not use Air2Sea for domestic travel unless the price was discounted (unlikely). I've used it twice for international. Both times the price was discounted.
Because you have other options for tipping, like in person or via the envelopes. I've never heard of putting it on your account. Seems dangerous for the reason you just experienced.
Those were unique itineraries specifically tied to accelerate the restart.
And they did go out to sea to start, but later overnighted there at CocoCay.