It should be able to correctly time most charges, so that you are always getting the highest battery charge state available at that stop.

Most kiosks have 30+ batteries, so each has a while to recharge before being 'summoned' again.

I can imagine it takes a few hours to fully charge these batteries (and to keep them cool), so if it's frequently used there wouldn't be any full batteries and swapping them would be a waste.

I mean it can be scaled up so that one of these stations has hundreds of batteries, an active cooling system etc etc, so it's a fixable problem.

Sure, but making you wait 20 seconds isn't going to make a noticeable difference there.

If swapping the battery takes about as long as sitting at a red light, that doesn't seem like a major problem.