(vibrate plates/shakers to rock suspension, mirrors to check rear lights etc )
non ATLs require a second person / helper
Many yest stations have "test viewing areas" so you can watch
I doubt many garages or test stations would allow general public in the work or test areas these days
it's an insurance liability due to "people" being STUPID ,getting hurt, then claiming compensation
much like everywhere ,"where there's blame ,make a claim"
Alternatively ... use common sense ,don't get injured in the first place
..... I presented an Astra G for test with a none working speedo/odometer. 
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