Why use encryption - as previously stated 'because they can'...other reasons are:
the radio system retailers push it and paid licences when often a simple PMR446 would do the required job
in the past few years fears about prosecution under data protection regulations (and the retailers pushed this as a reason long before GDPR)
Fear of buisness being poached (taxi drivers in particluar swithced to data systems but these weren't really secure and they started to move to data over GSM as the transport layer was then secure)
There isn't as much encryption in use as people imply but the GDPR has certainly made users look harder at whether they need to update radio systems for privacy. Lots of systems have been lost to GSM as the cost of that often beats commercial radio systems (historically far more expensive than the US and gives wider area coverage.
'entrapment' - the messages were only on frequencies which it was illegal to monitor so it's unlikely a court would consider it entrapment. The more amusing one was the audio message 'scanner trap' between overs on some police systems. Wish I'd recorded stuff like that back in the day!
TV tax - it's per residence not per TV set.
There has never been a proven case of detection from these leading to a court conviction. There is a huge debate about the methods used by CAPITA collect the BBC tax...cases that lead to prosecution are the result of people admitting they used a TV to watch live television (or BBC iPlayer) without a licence (effectively 'entrapment'?). The Capita employees have no right of entry. If you keep refusing entry when they ask they will eventually send a 'detector van' (I think they have three to cover the UK andf none appear to contain any radio equipment just a video camera to try and catch you apparently using a TV or 'evidence' of TV like, lighting). If they get this 'evidence' then they get one of their pet magistrates to rubber stamp a piece of paper worded like a search warrant (question whether a rubber stamped one is actually legal within the UK court system as a real signature is required?). - TV licence paperwork is by far the largest single user of magistrate time according to a magistrate aquaintance. - They then turn up, usually with the police (who are there to prevent a breach of the peace and not to ensure entry......Capita staff don't tell you that as it wouldn't appear quite so menacing ...I wonder if they pay for the police time?). Everything is geared to getting you to admit verbally that you use a TV and that is the ONLY thing that is used in any subsequent court case...no mention of TV Detector Van and no 'evidence' ever logged with the court that was sourced from the van!
The BBC say they are not responsible for the methods used by their agent, Capita, but a few years ago changed the tone of the letters sent out as they were threatening. These letters are sent roughly every 6 weeks to houses with no licence. They ask you to reply (why should I spend my money replying to them about something I don't need?). A very large slice of the TV tax is spent on trying to get more TV tax.
Fascinating subject for someone who has never had a TV licence
The comment about B&W licence surprised me as I thought they insisted on the 'colour' one nowadays as the cost of a B&W doesn't cover the cost of ensuring it's collected.
Duff info being added to RR - I replied about that at the time. The info also related to other European countries and I'm not privvy to info about who the submitter was.
The reality regarding scanner usage in Britain is that people are free to buy and use scanners and OFCOM don't have the manpower or will to enforce the law. USMC F35s in the UK at the moment and the anoraks have been out in force with their 125XLTs blatently listening to Swanwick Mil. If stopped by the plod they might be fined under the SARS-COV2 regulations, fined for parking on double yellow lines etc. but won't be prosecuted for listening to hairband despite it being illegal (unless you hold the relavent licence). Walk round the local cathedral of consumerism with a scanner to see if you can hear the staff moving manequins, shopwatch talking about someone in a suspicious hoody, or fast food headsets and no-one will pay any attention except another scanner user who might as you for the frequency or clues on how to enter a frequency on their radio.
ukradioscanning is a largely dead bulletin board with no active moderation. Looking at it I now It seems there is an unhealthy obsession with the idea that posting a colour code or talkgroup will lead to the end of the radio hobby....and people who can't be bothered actually using their expensive radios to find what is active around them. Very little up to date info or interesting discussion. It's clear there is a hidden part to it...perhaps that's actually alive?
As an interesting aside to the legal stuff - here it's illegal to listen to a lot of stuff but people ignore that. When I lived in the US people seemed to get a bit upitty about the law if I monitored things like pagers or (analogue) cellphones