So it sounds like it's multiple people at fault so no one takes the blame or learns for the future
If we're going to start at the top then I vote for British Exceptionalism and how we are so much cleverer than other countries that have ongoing or completed rolling programmes of electrification.
Because we were to clever to electrify, we needed high-performance diesel bimodes. But because we were also cleverly maximising seat counts, we demanded all the hot oily metal be wedged under the floor in a restricted loading gauge, adding technical risk and locking most IC operators into another 4 decades of poor accessibility.
All this inevitably made GB requirements more expensive, more complex and inherently less reliable than - for instance - a conventional EMU.
If the EMR bid team had not persuaded the Hitachi sales team to specify a new bespoke design with only 33 units ever built, then they wouldn't have won the franchise.
I agree - not being able to have a standard solution for the MML led to a micro fleet requiring significant redesign costs and technical risk.
Although I'm sceptical of rumoured competitors: 125mph bimode Aventra? Good luck with that. I wonder how Stadler were going to square the requirements to maximise seat counts and 4000hp of diesel power in a low-floor design.
Commercial teams in the client will look to contractual incentives and penalties to insure against under-delivery. This can work, but with very troublesome projects, the client eventually runs out of meaningful penalties to inflict on the supplier. At that point you may have an utterly dysfunctional relationship, with the supplier prioritising more lucrative contracts and raising a compensation event every time somebody coughs.
And finally, Etches Park seems to be really struggling from a capacity perspective to avoid being overwhelmed by the challenge of getting the new trains reliable, whilst patching the old ones up.