Roger did say at some point he was a bit fed up with drumming. He still did a great job when touring, but I suppose in the studio he'd grown tired of that and was more focused on programming, singing, and playing other instruments.
David Richards did confirm the samples came from his (Roger's) own playing.
I think maybe in early days (Hot Space era) on songs like Staying Power, Dancer, Cool Cat, and Body Language, that's a Linn drum machine (to my untrained ear) but once programming got more sophisticated he did most of it himself. I'm sure what they're showing in the One Vision documentary where Roger is hitting and playing different parts of his set is a stage of the programming process.
Its also is downt to the requirements of the song n question. The samples thing in the 80s was a bit different than today.
You could sample live drums (that means the drums Roger actually played in the studio) to make the snare drum more effective for example. A good way to hear this is Hammer to Fall. The every second snare drum hit is sampled with an more effective hit on the top.
You could also start to record your own drumsound to the sampler and play them back with LinnDrum. This is exactly what they did with Scandal. That is the reason why they sound much more natural than on Radio Gaga. But they are still programmed. That song is so sequenced and relies on that arpeggio, so maybe they descided to program the drums rather than try to get Roger to play it so precise.
Oh man. It is becoming ever so clear how the output from the 1970s was exceptionally superior to their later albums. I am suspecting that Queen began using drum machines on Hot Space, according to this amazing list here. I would blame Mack, but I'm sure that Roger used them all over his Fun In Space (1981) album as well. Holy smokes, is the drummer to blame? My mind is blown.
I would not blame anybody for this.
It was a natural developement in those days. Suddenly electronic drums were there and seemed to be "the future". Lots of bands went into this "trap" like ELO or even the Moody Blues. And what sounded modern then, very soon sounded dated. The moment you hear these terrible syndrums you know...it's 80s...
The interesting thing is, that they all tried sooner or later to make these electronic drums and drum-machines sound as natural as possible. If you don't have a drummer - yes!
But if you have a real outstanding drummer - isn't it better to let him play instead of programming a machine to sound like him?