It's not that they weren't told...
At the start of the planning, this was pointed out to the committee in very plain terms. It even persuaded them to look briefly at power line comms for the return information, which had worked moderately well in several other countries. At the end of the day, the decisions was largely based on utilities not wanting to engage with companies that hadn't worked with for at least twenty years, along with a fear of any new technology. If anyone had offered them analogue smart meters, they'd have jumped at them.
The problem is that despite having cost around £30 billion, there's no cost to the Treasury, as all of those costs have been added to consumer energy bills. It means that the Government isn't really interested and OFGEM probably see it as a gravy train, as they can fine the utilities for not meeting installation targets. So just expect more of the same.
It's also one of those projects, like HS2, which every party has had a hand in, from Labour, through the SDP and Tories. So unless the Tories lose a byelection based on Smart Meters, we're probably set to throw a few more tens of billions away.