They can get away with it because Apple fans (even the ones who are tech-literate) react with visceral disgust when anyone suggests and Android phone or a non-Mac PC.
It does not hurt that Android and iOS are both kind of the same OS now. Yes, I get that there are a million differences between the two, but now that we're at almost two straight decades of the platforms copying features from one another, the difference is academic for most people.
I don't think that would be a good idea for two reasons:
1. Trump could decide what to apply the negative tariff to (e.g. Trump merchandise or his buddies)
2. If there's a fixed amount of money to dole out and suppliers know it, approximately zero dollars will be given back to consumers because it will be easy to capture the money on the importer side.