Rebroadcasting and streaming of these 27.5 services is happening on an industrial scale, and a few people are making large amounts of money.
It enables streaming head-ends to be located outside the EU. UK broadcasters have a very limited ability to prevent such piracy. Introducing higher levels of encryption must be part of the plan. Those who post BISS codes in the name of 'freedom to view' are aiding those involved in reselling BBC and ITV services.
There is also the issue of the tens of thousands of UK expats living in the Algarve and the Costa Del Sol, often elderly, who lost their BBC. Many have been persuaded to buy 27.5W systems. Some are effectively trapped in exile, unable to sell their homes or return to the UK, often short of money. They are easy prey for scammers offering to get their TV working again.
Even BBC insiders argued against moving services to UK narrow beam, but they were overruled by executives eager to scale back the cost of acquiring broadcast rights. Whether this is right or wrong, it isn't going to change in the short term. The priority now is restricting viewing to the British Isles and near continent.