Yes, you can get a random PC that is faster than a Raspi for cheaper. But it is a random used PC which you have to individually set up. Not counting that it is much larger, usually not portable and needs more electricity.
The Raspberry Pi 400 is a pretty much usable desktop computer out of the box which you can buy as a complete set for 100€ new, including a nice book. It is also very nice to use as it is compact, very portable and doesn't need more than an USB power supply.
In comparison it is very easy to grab an used screen, as the screen doesn't need to be set up. In addition, the Pi works well with a current TV. Brings back the best of the home computer age in the 80ies.
I'd agree that, in a teaching context, it's vital to have a consistant hardware / software experience - especially with beginner users, even different keyboard layouts are going to cause confusion. The Pi 400 is a great device, nice and compact - if you get the starter kit you just need to add a monitor / TV. That does somewhat assume someone has a bit of room, though - some space to plug in to what might be a shared TV. The really nice thing about Raspbian is that is does actually work on older laptops (with a couple of catches - no free Matlab), so, if you have an older laptop available and can spend a bit of time setting it up, you can give someone a very similar experience on a more all-in-one device.
The Raspberry Pi 400 is a pretty much usable desktop computer out of the box which you can buy as a complete set for 100€ new, including a nice book. It is also very nice to use as it is compact, very portable and doesn't need more than an USB power supply.
In comparison it is very easy to grab an used screen, as the screen doesn't need to be set up. In addition, the Pi works well with a current TV. Brings back the best of the home computer age in the 80ies.