[Zenbit_UX]

You can reach everywhere in 5 days but that's not enough. People have to come and get it, there's also a chance there will be a slow start due to concerns over a new drug that the media may emphasize was "rushed". Then there's the logistics of scheduling so many people. If you don't bring yourself a cold storage freezer you're committing to using 100% of your doses within 5 days which may not be possible.

[bluGill]

For the first few months all doses will go to high risk people. Most won't have the option to refuse it.

Eventually you are right. If the Pfizer vaccine is to be used in remote places the people getting the vaccine will need to schedule it in advance (and probably pay for it) to ensure that once it arrives it is used.