I never heard of this, where in Europe?
I'm not sure why this is allowed as these things are noisy, unsafe, and hold up all other traffic. And they are not limited to disabled people either, anyone can drive these.
They used to look terrible and nobody wanted to drive them, but since they don't require a full driver's license and are not taxed annually, they have become more popular, and now look mostly like regular cars.
Search for 'brommobiel' or 'mini car' to get some examples.
What the law intended: https://alleverzekeringenopeenrij.nl/wp-content/uploads/brom...
What you can actually buy: https://media2.autokopen.nl/auto/brommobiel-aixam-crossline-...
That last 'car' has a whopping 8 hp.