In the Defence industry, they can and will search vehicles and property. Accepting a job is assumed (sometimes explicitly contractually stated as) giving consent. You must generally assume that company machines and comms means are monitored at all times.

Plenty of employers can and will search your belongings/vehicles you bring on their premises. Think the NSA or prison workers for example. Or even bank employees. Anyone who works in a secure facility (Think civilian employees who work on a military base) are subject to search as well.

Again, property rights. If you choose to park on their property, they can search, just as the TSA searches people who enter airports.

(There's some more rules, since this is a case where property rights conflict, so generally they have to notify about the situation upfront.)

Is that the case even if you are using your vehicle for a delivery service and they suspect you of stealing stuff?

Yes, if it is your car, they cannot search it. (Unless, as others said, it is a secured area, and by entering you give permission to search your person and property.)

But if you deliver for Papa John's, and they think you swiped some stuff, they can't search your cat.

Of course, law enforcement may acquire a search warrant, but that applies to everything, employer and employee.

> But if you deliver for Papa John's, and they think you swiped some stuff, they can't search your cat.

I think that this discussion is old enough now that it is safe for me to say how much I enjoyed the mental image conjured up by this typo.