Will an android phone alert me if I’m being followed?
Will an iPhone alert you if you're being tracked by a Tracki/Tive/Lightbug GPS+cellular tracker? These are common in commercial shipping, but easily accessible for consumers too Here's [1] for $16 (requires $20/mo monthly fee) and [2] is a bring-your-own-SIM off-brand device for $20. Or, heck, they could just get an actual Android phone (either just an old one they have in an electronics drawer, or they could buy a used low-end model for $50), plug it into a 12V charger in the trunk, and set up location sharing.
To be clear, I think Apple made a reasonable effort to do the right thing here. The difference between Tile and AirTags is that the AirTag has a scale factor and pervasiveness that enables 'crimes of opportunity'. It's infeasible to prevent determined criminals: if you have to plan purchasing it, and signing up for the subscription with your personal details, and wait for the shipment, and install it, most people will think twice before following through with that whole sequence. On the other hand, if coworker A is preparing a laptop bag for coworker B to take home, and is fidgeting with the AirTag on their keychain while they do it, their impulse control might not be sufficient to prevent them from slipping in the tracker that they already have on their person.
If there are no iphones nearby, the airtag doesn't work.