I was curious about how much more Toyota could fit in that same volume if using state of the art batteries.

The 2021 Tesla Model 3 LR has a pack volumetric energy density of roughly 240Wh/l.

The 2017 Prius Prime has a pack volumetric energy density of roughly 150Wh/l.

So ignoring Toyota's poor battery placement, you could fit ~14kWh in that same space in the Prime using a better pack design with more modern batteries.

If Toyota pulled their heads out of their asses and actually designed a car to be an EV, they could match Tesla's battery pack sizes and still have reasonable trunk space.

I say this as someone who owns two Priuses and do not understand why they didn't capitalize on their advantage to design a decent EV years ago.

The number of Priuses sold per year in the US tells a story of Toyota absolutely failing to capitalize on new technology when they had the lead: https://motorandwheels.com/10-toyota-prius-statistics-facts/

To be fair, I have 3 cars, none of which have spare tires. Teslas don't have spares, either.

For most people, calling AAA is probably the way they're gonna go, instead of changing their own tire.

I am fascinated by this world we've created where something as basic as carrying a spare is now considered unusual.

Tires don't fail often anymore. A blow out was a regular thing that happened to everyone once in a while, in that world everyone had a spare and knew how to change it. Today tires are a lot better (and last a lot longer), most tires make it to end of life with no problems. It thus doesn't make sense to dedicate volume and weight (read fuel mileage) to a spare tire that won't even be used. As such it doesn't make sense to have a spare or know how to change it, just let someone else do it.

Do most punctures result in a slow leak?

Yeah; and on-board tire pressure monitoring was mandated in the US as of 2007, so typically you'll catch it before it's an issue.

I guess they figure few enough people know what they're doing, feel safe doing it at the side of the road without an emergency vehicle with lights watching out for them, using a janky scissor or bottle jack, and the problems are rare enough that why bother?

And then most peoples' spare tires were never checked so they're underinflated/rotted and unsafe anyway.

In most cases, if I got a flat in a car with a spare, I wouldn't replace it at the roadside with my spare anyway. I'd do.. something else. Get a free tow from AAA to the tire shop (because I'll need to get my tire fixed ANYWAY), get a ride home and get a real jack,... but not use an unsafe trunk kit jack on the side of a freeway.

in my experience.

I'm not a tire expert, but it seems to me that the blowouts of the past were a quality issue and not caused by punctures.

What do you do without a spare?

The Tesla has somehow gotten 2 flats in 3 years / 50k miles. I attribute that to racking up commute miles on heavily travelled/littered urban freeways. First one, used roadside, wheel+tire delivered to us but it took an hour as it was in the middle of rush hour. Still had to sort out the original tire and return the loaner from Tesla. (tow company they contract with stocks Tesla loaners, I guess). The other was going low slowly, caught by TPMS, just dealt with it at my leisure.

Other car without a spare, had a flat once in 15 years, it was sitting in my driveway, dealt with it in the usual way.

Other other car without a spare came with runflats but I replaced with "normal" tires. I carry a plug kit and a compressor, and pray?

But normally, AAA or similar. I have roadside through my insurance and also separate AAA coverage. On long trips I try to make sure I have cash to pay local helpers/tow trucks/etc.

In the case of Tesla, you call Tesla Roadside. For other cars, you use the fix-a-flat kit or call AAA/other roadside service.