Well, ULX has nothing to do with picking up cars, so if you're expecting that to not happen, you're asking in the wrong place. ULX is not a prop protect.
And, if you're using some addon or mod that would control picking up of stuff based on access level, it may have no idea that, according to you, headadmin is higher.
Gmod, by default, only knows three access levels, and superadmin is the highest written in to Gmod by default.
