I suspect a lot of it is due to the sheer difference in the amount of UV exposure you get inside, as against outside in full blazing sun.
That's why the leaving outside for an hour or two trick works in the first place, to give a similar degree of change that takes months if not years at indoor UV levels.
And why garden furniture takes *so* much more upkeep to keep it from fading out to silver-grey - I've never seen an indoor piece of furniture get anywhere close to beginning to do that.
I'm speculating, though, not having tried it, but I'll bet after a week or month or four, even US cherry would begin to fade again. I've never heard of any wood that doesn't go silver in the end, exposed to enough UV.
I suspect the A+B bleach is infinitely more practical.