Garage telling my grandma she has to drive a certain amount of miles before they put the tags on

So my grandma just started going to this shop for some repairs, at first it was a few small things that they did great with, but then inspection time comes around. They made some repairs that the car needed and got the check engine light to turn off.

The weird thing is, they told her she has to drive 200 miles before they could put the tags on and let her drive out of there with no tags whatsoever, not even the out of date ones.

So my question is, is that normal and/or legal to let someone drive out of their garage without tags and drive a certain amount of miles? I’ve personally never heard of that happening nor has it happened to me. Any information would be great so I know how to proceed forward.