Hard to say. At one time you could turn up and sit a City & Guilds exam, of course to become a bonafide amateur you had to pass the Morse test, but they've relaxed that now. I went from UK Foundation licence to Full licence in about a year, not difficult from a technical point of view as I was working on 500kW broadcast transmitters at the time. The questions about the arcane rules and regulations were probably the hardest. UK amateur radio is quite set in its ways, the average age of UK amateurs is probably around 60. Some of it probably stems from elitism and from some of the UK history of radio piracy.

https://en.wikipedia.org/wiki/Pirate_radio_in_the_United_Kin...

http://www.laughingpoliceman.com/amateur_radio.htm

My father wanted a license and found it incredibly difficult to get in contact with the nearby group, only to find out (when he eventually managed to get in contact) that they wouldn't be holding any exams for some significant period of time

Just seems like a clusterfuck to get the damn thing, the foundation exam is dead simple. I'm totally unsurprised by the dwindling popularity of amateur radio here. Even if the difficulty isn't the driving factor, I'm sure it deters lots of people who otherwise would be interested.