This particular fiasco should be blamed not on those who PROCURED the IETs▸ but on those who BUILT them.
So this failure is down to Hitachi "you built them, you make them work"
Totally agree with you there -
but many/most/all of the large contractors out there who bid for Government work of all sorts know full well that this procurer never enforces its legal rights.
Trains, aeroplanes, submarines, hospitals, motorways, PPE, rail electrification, etc, etc are procured with the supplier knowing full well that if it doesn't meet the spec then the only way for the customer to get it fixed is for him to cough up more taxpayers' money. Then depending on the end user the money either appears - or doesn't - the rail passenger comes well down that list. So it is highly likely that the IET will limp on for many years to come (except past Dawlish of course)
No one tries that trick on Tesco, John Lewis or M & S - not more than once anyway !
Been there, seen it,
done it, had it done to me !!