My Nexus 6P starting having spontaneous shutdowns at 15-30% over the past few months. I replaced the battery and it's back to normal. My old Galaxy S4 before that had similar problems after 3ish years.

So a feature to throttle the CPU while I waited for a battery replacement on Android would have been great I think! It needs to be toggleable and it needs to clearly surface to the user what the long term fix is though (i.e., replace the battery). Apple's solution did neither of these, but if it did I think it would have been fine.

All of the Android phones I've had do when the battery starts to get old, Especially when you use the camera while it's low. Maybe you take better care of your batteries?

My 2013 Macbook Pro would spontaneously shut down with anywhere between 30-40% battery. I tried a few tips I found online to fix it, but nothing seemed to work.

This post gives us an estimate for what percentage of the iPhones are getting throttled by this issue. I think it's reasonable to use this as a proxy to estimate how many units were at risk of shutting down and it is the minority of units. Happily it appears both of your devices are in the majority of units which don't exhibit this issue.

https://www.geekbench.com/blog/2017/12/iphone-performance-an...

If I read that correctly, is it 25% of two year old devices (6s) that are getting throttled?

Have your android get any update after a year? Doubt it.

If you do, are they even functional after the upgrade? Mine became couldn’t do anything because it is so slow after upgrade.

Only good thing was I had an unlocked boot loader and able to flash the original Android back

Please don’t act like Android is anything better. It is not.

My 5 year old android gets the latest updates, and I don't have that issue either. I agree Android's are POS, but that doesn't detract from the fact that iPhones are also POS.

what's so special is that modern iPhone CPUs are as fast as laptop CPUs (when untrottled).

This. iPhone has been the industry leader in CPU performance and integrated processor functionality for a while now, I have no doubt that plays a role.