I think the propaganda is the nefarious reason.

Tories have been talking about this since at least the coalition, if they had really wanted to impliment something like this they would’ve. The fact they haven’t implies:

• They don’t actually want it. Judging on recent scandals any chaste puritans in the tory party are so far in the back benches as to be blind to any goings on up front.
• They want to keep talking about it. See also: immigration. They know they have shit policies in every other area, so they need ‘vote winners’ among their core demographic (50 and over). Hence: save the kids, stop the boats, shag the flag. Labour and Lib-dems are never going to be able to present themselves as credible in these areas because of their historical leanings, so the tories don’t actually need to back up their promises with any actual ‘progress’ on these issues.