Caution: Do not operate forklifts

Actually they are referring to fork lifts too. Cranes, bailers, front loaders, etc. that’s why they say heavy machinery. Lots of people routinely have to use machines like this for work etc. So the medication warns you. You’re likely fine to operate a toaster or a toilet handle or an egg beater, but the drowsiziness or disorientation such medicines can cause makes operating heavy equipment dangerous. While any machine should have full focus of the operator- in practice the odds of a catastrophe occurring from negligent operation of light machines caused by these side effects is low and the results aren’t on average as realistically potentially disastrous. The millions of people operating fork lifts every day could use a heads up not to do so while on that medication. The average office worker probably isn’t operating a fork lift or bailer but a car would count for sure.

Same here.

Generally they say vehicles and heavy machinery.

Bulldozer