433MHz really is a strange band for a few reasons. For one, it is shared by license free devices and also Amateur radio, not only can amateur radio operators use this full band with very high power for long distance DX contacts but also it is the same band that is used for car security fobs (that lock and unlock cars) along with other security devices such as garage door openers, these operate on frequency 433.920MHz.
This means anyone using a ham radio on 433.8200 MHz or even nearby frequencies near cars will be blocking out people from accessing their vehicles. I have had first hand experience of this when speaking to a friend we legally were using 433.550 which is not only license free (you can buy walkie talkies on these frequencies for your kids) but it is covered by our ham (amateur radio) licence. We were having a quick chat in a car park and panic ensued. No one could open their cars with their key fobs while we were transmitting, and we were not even on 433.820, just close-by on 433.550.
Some managed to get into the cars by using their key which set the alarm off as they had not deactivated the alarm with their fob however most were simply locked out with no way of getting into or locking/unlocking their vehicles.
It seems a very strange place to put a lot of users who are unavoidably going to cause interference to each other, surely somewhere around 1.2GHz would be more suitable?
It may be an effect of the mind control powers this frequency apparently has, according to one YouTube user 433MHz is used for Nazi Mind Control, you can see his video here
I don’t know which is crazier, the suggestion it is used for mind control or the decision to clump all these users together in the same band?