You have people over 75 years old who were waiting and registering on whatever reservation system was cobbled together on short notice, and then because the public health authorities now risked throwing out doses for want of people to inject them into, they just opened the floodgates to everyone over 65.
So what happens to the people over 75 who were waiting, and now are swamped by the crowds? If they keep on opening up bulk tranches of the population (instead of in small slices) before people of priority are reached, when will the most vulnerable ever get their turn?
This is a known problem. Multiple queues of priority and people on call to be given turns the next day if it looks like there's capacity.
Instead you have people wondering if they should walk in, visit a county next door, or wait around in case some mistake is made and there are actually extra doses at the end of a day. Or try to scheme/figure out the system however they can, out of desperation.
If it can't be done right, let everyone know that it's up to their willingness to wait wherever they can, according to some basic ground rules, and don't make a meaningless (or worse, deceptive) reservations system that gets bypassed at the last minute.
What a shameful clusterfuck.