My guy doesn't do this except for a quick sanity check. Or maybe because patients expect it? They have your prescription the second you look in the auto focusing machine. Hell, someone invented a lens for a cell phone that does it.

The optometrist is looking at your eyeball health and related medical issues. The clicky thing is mostly performative.

If it isn't obvious, you're done. The weaker of the 2 lenses is right for you.

If you don't see a difference, you are already very close to the optimal correction and a subtle change in either direction is unnecessary. They will still go ahead and try fine-tuning the prescription and when you tell them that A and B are the same, they can fall back when they add another correction. A and B might currently be the same, but if you add C, A+C could be better than B+C.

“Same” is a valid response. I’ve never had an optometrist challenge it.

You know, it makes me wonder how that works. Because most of the time, they get the prescription right, even though, for the most part, we only guess which one feels right to us, even though, to us, one and two look practically the same.

Where I'm from, optometrists always ask "one, two, or are both the same?" I've never had any issue with that.