The whole operation depends on two things, first people having a smart phone and secondly that they download the app.
Neither of which are compulsory or enforceable. So just relying on a certain amount of the population abiding by this.
This almost smacks of a lockdown by the backdoor. I know this relies on people having an up-to-date smartphone with the app downloaded (mine's too old and won't accept it) but when most people theses days seem to need the latest tech and feel the need to be contactable every minute of the day and tell everyone they know, on or off social media, where they are and what they are doing it's easy to see why so many are getting the ping.
[I only swapped my dumb phone for a smart one when I needed to use it as a modem when I was away and had no other access to broadband. 95% of the time my bluetooth & data is switched off and it's quite amazing how long the battery life lasts than otherwise might be the case.]
Because I have no app and no bluetooth on I'm not going to get a ping. Neither is it a legal requirement now to check in via the NHS Track and Trace so I'm not going to. After 16 months of restrictions I am fatigued with it all and also pissed off at other people flouting or blatantly ignoring the rules when most of us have done the right thing.
If, however, I have knowingly been around someone long enough who has been confirmed positive with C19, or if I develop Covid-like symptoms I will get a test and self-isolate.