Jack
Perhaps this is confusing, but if you are level 12 you can hire "up to level 12", not beyond level 12. E.g. 11.99 would be the highest level you could hire, which would be displayed as level 11 in the interface.
I suppose it would be much easier to understand if it was actually "up to level 13" for drivers and staff, since they actually have decimal levels on the back-end.
I'd be interested to hear if anyone else has an opinion on whether this should be changed.
If we can't see the decimals then they are not there as far as we know. So it just looks like a lvl 12 can't hire a lvl 12, regardless of what the backend reason is.