I think Apple is trying to avoid "battery obsession" in iPad, because for the average user iPads don't have the same battery performance challenges as iPhones. The whole "Throttle to avoid shutdowns vs. let the thing shut down if the battery can't deliver the required peak current" thing has not been the major issue on iPad that it is for iPhones. I think it all comes down to the sizes of the batteries.
Both iPhones and iPads are running (essentially) identical processors and apps, so peak current demand is going to be quite similar. However, their batteries (due to the dramatic differences in size) have very different peak current capabilities. (The iPad's larger display demands more current on a constant basis, but the display doesn't make the same kind of peak demands the CPU does.) A three-year-old iPad battery can probably still deliver all the peak current most apps require, while a three-year-old iPhone battery may already be toast.
Essentially, Apple is being Apple in the sense that they don't want to draw attention to the iPad battery (by providing comprehensive battery condition/usage info) if it isn't a major problem. Without a doubt there would be those who see a Maximum Capacity in Battery Health of, say, 87% and decide they want a new battery, regardless of whether 87% is a problem. (In theory 87% isn't a problem in an iPhone either, but an iPhone battery at 80% is a problem, while an iPad battery at 80% probably is not a problem.)
Now, I'd love to have the same battery info for my iPad as I get for my iPhone. Enquiring minds want to know, and all that. However, I'm still seeing no hint of battery problems with my first-gen 12.9" iPad Pro, which is more than four years old.