To operate a model plane, there was a not-small amount of effort you needed to work through (building, specialist components, local club, access to a proper field, etc.).
This meant that by the time you were flying, you probably had a pretty good understanding of being responsible with the new skill.
In the era of self-stabilising GPS guided UAVs delivered next-day ready-to-fly, the barrier to entry flew down.
And it took a little while for the legislation to catch up from “the clubs are usually sensible” to “don’t fly a 2KG drone over a crowd of people at head height with no experience or training”