Years ago - I'm talking the '70s and possibly the '80s - cruising was a flat fee. There was no breakdown of taxes, port charges, etc. The only additional expense would be tips which were handed out on the last night to stewards and wait staff. This was cash in envelopes.
I only remember that "someone" made a big stink about it, so the change was made to list each item separately on the invoice. I say "someone" because I don't know if the change was made due to complaints from passengers or if a state or federal agency stepped in and forced the change.
This was also well before the internet. One would go to a travel agent, book a cruise, pay the bill.
Personally I didn't mind the change in the way invoices are now handled. I don't do the extras.