Well, what I’m thinking is that Gary must have owned the garage, or was blood kin to the person who did (say, brother,) because I don’t see any employer allowing an employee to let their daughter do anything so technical - or so risky.
Liability is a thing, after all, and letting Lydia do work like that would be exposing the garage to massive liability in the event of something really, really bloody and awful - like an engine block falling and crushing her finger - happening.
And if somehow it did happen, I don’t see Gary having the option to leave his job or not; he’d be sacked almost immediately, unless he either owned the joint or was, again, kinfolk to the person who did. “Bring your daughter to work day” may be a thing, but in the event that said person works in a risky environment (say, an auto garage,) said daughter, if permitted at all to come, would likely be sat in a chair or something and told to watch but not touch anything.
I mean, it’s a good reason for her finger to have been mashed, and “pulped by an RV engine” could certainly destroy a finger beyond medical salvation with the technology we have or are likely to have in the near-future, but…
Though actually, with CDDA being a near-future, it occurs to me that she might have had the opportunity to accquire a prosthetic - a bionic finger - nothing mechanically advantageous, just a replacement.