Why dont all lenses come with date codes?

I just picked up a new lens and started thinking about date codes. I know non L lens do not have the date codes, but why not? I think it would make sense for Canon to put it on there, and be able to track all sales/returns/warranti​es.
What do you think?

Maybe a varied process they use to make them that makes it harder to stamp them?

I really honestly do not know.

Angry Dad wrote in post #7602085
I just picked up a new lens and started thinking about date codes. I know non L lens do not have the date codes, but why not? I think it would make sense for Canon to put it on there, and be able to track all sales/returns/warranti​es.
What do you think?

They can track all that without any problems using the S/N.
The only difference is that users can't figure it out by themselves.

Rodinal wrote in post #7602540
They can track all that without any problems using the S/N.
The only difference is that users can't figure it out by themselves.

Can you elaborate a bit? Im not sure what you are talking about.

The serial number is recorded by them, when they look it up they can find date of production.

Date codes aren't exclusive to L's but they're not on "consumer" lenses.
The TS-E45, TS-E90, MP-E65, EF50CM and many others still have regular style date codes.

Bob