Indeed. The bids must be evaluated strictly by the criteria set out in the invitation to tender, and if a bidder ignores a mandatory requirement then they will fail the evaluation.
Absolutely, and I agree with the rest of your post also.
I had experience of responding to tenders, then experience of writing tenders, I changed jobs, poacher turned gamekeeper if you like. Nothing to do with DfT, mind you.
In the first case, I remember a £100 million tender we won, on which I was not involved until the last week, when I was asked to work with the bid team to ensure that we had correctly responded to all the questions.
So I start to wonder why a non-compliant bid would be submitted. Perhaps it's to make a point, but then I remember a much smaller bid which I initially advised against competing for. My company couldn't work this out, so spent a lot of time and effort putting together a bid which eventually it never submitted. My failing for being unable to make my point clearly enough, I guess. Too many other people with a mindset of "we must try to win this business" in some way. So either a big mistake or an expensive way of making a point by being deliberately non-compliant, or possibly a hope that all responses would be non-compliant in the same way?
As gamekeeper I remember receiving a response which could be read as non-compliant. We asked the supplier a very careful question in which we asked them to clarify, but trying not to give the game away or giving them an unfair advantage. They answered correctly and went on to win the business. We didn't want to disqualify them on a "technicality" but needed a better answer than they had given to ensure they were compliant. However if they'd given the wrong answer we would have disqualified them.