Interestingly, the RAF picks its TSW guys and gals mostly from those with a bit of experience in the basic trade and they are usually SACs. If the Army followed the same process, the entire refuelling mob would be at least lance corporal (bit like the RMP here).
No, they would be Class 2 privates, not NCOs. Possibly even a class 1 private, if they were not yet NCO material. Nothing at all like the RMP, where shiny new coppers are LCpls, and after a year they get their Cpl. All of it paid, BTW, not like the LAC (ACpl (UPD)) RAFP.
It's an age old debate, with the RAF counting promotions, and the Army making determinations based on whether the guy is an NCO or not. The same debate occurs wrt WO2s and Flight Sergeants. No Warrant=not equivalent.
Suffice to say, a lance-jack can (in theory) discipline an SAC.
And be crap with fuels.