Stickers work too, but I'm guessing that in their case they just don't want to deal with applying stickers to a lot of keys and then removing them. We also had to put some stickers on vending and coffee machines.

We used to be audited every year but after we made a lot of progress they starting coming once every 2-3 years.

I think they started auditing after complaints, we're a manufacturing company in the suburbs with 99% French speaking employees but a lot of the stuff we had was English only. Fun fact, our parent company in Texas was careful and made sure we had French documentation/communication but French speaking office employees didn't seem to care.