All the computer achieves is to force the tester to make the test last at least 35 minutes, it does bugger all else.
I had my own pad and stamp 
Back in the early/mid nineties we knew a tester that used to take the book & stamp to the pub with him during his lunch break and write them "blind" for £50 at the bar while supping his pint (a straight MOT at the time was £25).
Life was far simpler in those days. Nowadays, you computer whizz kids have got it sussed, us boneheads have to pay for everything.
Oh I still have to pay for the MOT, but her godfather can be quite lenient when conducting the actual test

The computer has made life slightly more difficult as you do have to present a car for it to test the emissions, but it has no way of knowing what car it is testing in the same way the ANPR computer doesn't know who is behind the wheel when they drive past.
A computer (like anything in life) is very easy to circumvent once you know how the system works.