Glass lamps have "etches". But are they ever really etches? No, they are stamps. With ink. We never actually etch into the glass of a lamp. If we did, then they would be very very durable and last practically forever (like they do with some vacuum tubes), but we don't. Anyway, they don't last forever and can just just wipe right off if they are old enough. This obviously isn't good if you are trying to replace or identify a lamp that has an illegible etch (I've been there).

Sometimes there are etches that are on the inside of the glass, that way they can't rub off. That works great, why don't we do internal etches anymore? Maybe they are not always practical for all lamp shapes. I would also imagine that could be problematic for sodium lamps with a high vacuum outer envelope.

If you wanna get really fancy you could do those ceramic decals that are found on labware and the like. They are still on the outside, but very very durable (I can't even scrape them off with HSS lathe tool). These decals are not expensive, and can be fired at the same time that the lamp is being annealed (assuming the lamp gets annealed).

I feel like a lamp company having durable etches would be a nice low-effort edge over competitors. And nice for us too. Idk

In my experience, the newer stamped etches tend to hold up pretty good. I have no problem when I am cleaning newer lamps. However, pre-1990s GE lamps do give me trouble. I’m not sure if they were always like this, but those etches wipe off CLEAN.