On Mon, 17 Jul 2017 08:51:27 -0700 (PDT), trader_4 wrote:

Why is that the standard?

That's a fair question. AFAIK, there are only three options:
1. Leave them yellowed (free)
2. Buy new headlight lenses (~$120 for the pair at discount)
3. Polish them up (~$30 for the pair at Sams Club or ~$30 for chemicals)

I haven't seen anyone claiming that they
will restore them to be indistinguishable from new.

Maybe I had simply *assumed* that they would be indistinguishable from new.
Can someone who has done it tell us how they compared to brand new?

I used a kit, I think it was 3M, worked great.

Three kits have been mentioned most he
1. 3M
2. Sylvania
3. Blue Magic

Most kits seem to have two parts:
A. The stripper
B. The sealer

It included an attachment for
a drill with pads. There was a huge improvement,
I was very happy, but no way I'd say they were indistinguishable from
new.

This is good to know because it turns out that the original owner called
today when we asked about some of the paperwork saying they had in their
garage a brand new unused driver side headlight lens, still in the box,
which they'd give the kid for free.

So now we have only one lens to "match" to the driver side.

It lasts several years, but obviously the process continues.

There is an open question as to whether the erosion process is
*accelerated* by the polishing, or if it's the same process, but starting
fresh.

Same thing will happen with new ones. The choice is up to you, but
I'm sure you're not going to find new ones for $10 which is about
the cost of the polishing kit.

Most kits seemed to come out at around $30 for the two components.
But I didn't look all that hard yet on price 'cuz I'm just looking at
chemicals right now.

And the lenses were poly or similar,
not glass (does anyone still use that?), so the part about it not
working on anything but glass is BS.

I agree. Glass isn't the problem here, at least not with the Camry.