The other thing to keep in mind is that a lot of US vehicles are missing the same safety features. Where's the seatbelt and airbag on a motorcycle, for example? A lot of semis also don't have airbags at all.

Even at 55mph they're actually not that unsafe in a sane country with sane cars- the driver is so high up that they're 'above' the crash (t's the same reason semis don't have air bags- they're not as needed)

... unless you're in the US and driving around a dick-measuring contest pavement princess that puts you eye level with a semi truck so you can murder small children easier, that weighs 8000lb.

Yes, they can't go 70mph, but that basically just limits them to not being able to go on highways and interstates, which is perfectly fine- frankly, we need to have less things being hauled that way, the highways will last longer and our microplastic issue will be largely solved if we stop shipping things in the single dumbest, least efficient manner.

Finally... modern kei trucks DO have a lot of those improvements. They have airbags, seatbelts, all the modern safety features, and can go 60mph. Keep in mind, in most cases semis have to go 5-10 under the speed limit anyway, which means they can basically hit the same speed limits as semis. We just aren't even currently allowed to import the modern kei trucks.