I was going to suggest putting signs up that clearly state the search bar isn't Google, but I realized that even if you did, they would likely get ignored. You may even already have them up.

Used to work in this exact environment. This tormented me daily.

Along with crap like "You look pretty smart." or "Hey I bet you're a genius."

Or just typing their email address into the URL bar.

Or just barking at you "PRINT."

Or "Why this no work, I click 'E' for 'internet'." (We had a stubbornly archaic IT lead who insisted on keeping Internet Explorer around for ages.)