I don’t know of a British armoured unit’s losses overall over the same period. There is this http://jramc.bmj.com/content/jramc/123/2/65.full.pdf which shows the losses of the British Armoured regiments with Shermans, Cromwells and Comets in 1945, which are approximately the same in terms of tank losses but show the same great disparity in terms of casualties.
“The US Division’s figures, taken over 10 months represent a baseline for the kinds of casualty figures that an armoured division suffers over the campaign; intuitively one might expect it to be the other way around.” Why? I’m not looking for a fight, I’m intrigued at your thinking. Unit A could be heavily engaged over a couple of days, but suffer relatively few losses. Unit B might be heavily attrited over the course of nearly a year. You can’t extrapolate B’s losses from A’s, or vice versa. Can you?
No, you can’t extrapolate losses, totally agreed. But I don’t think the article is doing that. It is asking why a second-order effect, the crew casualties as a result of AFV destruction, should be so radically different. I’m not really sure why that comparison has to be over the same time period, since it is broadly with the same equipment facing broadly the same enemy with the same equipment.
However, since you consider the comparison pointless and I agree that it is hardly a thing to fight over anyway, it doesn’t really seem worth discussing.