These are paying customers, discouraging them from coming back is a net loss. Suppose your cabin includes a shower but you need to pay every day to actually use it. Nobody would think that’s reasonable, but because internet used to be difficult companies are still tacking on insane fees even though the actual costs are minimal.
With Starlink you’re looking at a lot more than 15mbps. We’re at the point where some cruise lines offer free Wi-Fi and people still see multi megabit connections anyway.
Commerce includes many unspoken agreements. Order a meal at a restaurant and expect to pay list prices +taxes etc, you don’t expect to be charged for using the salt on the table, or the price of a doggy bag etc. Airlines don’t charge people to go to the bathroom, though they may reserve better bathrooms for first class etc.
Companies breaking with these trends face a backlash assuming a competitive marketplace.
Reasonable is not wanting to be nickle and dimed for every amenity that could possibly be split into a separate cost.
Prices for such add-ons, especially ones that your average customer won't think of before, are also often unreasonably high because the operator knows they have a captive audience they can exploit - you either buy from them or go without.
With Starlink you’re looking at a lot more than 15mbps. We’re at the point where some cruise lines offer free Wi-Fi and people still see multi megabit connections anyway.