An employer disabled the weight and balance system on their 747F Classics because it was too unreliable and expensive to maintain. The system on the 744F continued in operation so these systems have been available for some time.
However, just having a readout of weight does not preclude the possibility of a transcription or calculation error unless the weight and balance output is applied directly to the FMS and engine control.
I have never seen a system such as TiiberiusKirk proposes. I'd have thought it would be very cheap to produce and may be of real value. CAA may, of course, want their cut for certicication. Back in the day, I believe the V Force used a line on the runway as an acceleration check - oops a black car has just pulled up and six big guys in black suits are getting out
p.s. posted before reading Dani's comment.
Oh, yes, wasn't the original article a load of pants.