Owners will always be responsible for their share of transportation costs that service the resort to/from the parks. So, if it costs a resort (making it up) 1 million a year to have buses bring guests to/from the parks every single day, then owners at that resort, whether shared or hotel, will pay a portion of that bill.
It is not just the construction of the dock or bus stop, etc. Its the operation to run it do, so CM's salarys, gas, purchase of vehicles, etc. When it is a shared resort, the "share" that
DVC owners have to pay can be determined in a certain way...and one way is occupancy levels at the resort (how many rooms are DVC vs. cash).
Its not just tranportation either, its any expenses at the resort. PVB owners pay their share to maintain the entire complex, including areas that are around the cash side....
But, with the shared hotels, if Disney decided they wanted to add an enhanced transportation option to service their hotel, then DVC owners, by default would have to absorb their share of operating costs for that transportion.