I think I agree, there is a lack of support (practically and financially), and if we want people to isolate when they show symptoms or have been in contacted by Track and Trace, we need to make it as easy as possible.
My own experience of isolation (a cough during the early days) was that the problems were purely practical. I was already working from home, so no impact on my income (and I am lucky that my employer could commit to paying any staff who could not work in any case). The practical problem was getting shopping. No supermarket delivery slots, no family nearby or close friends nearby that I could ask, not particularly close to my neighbours (most are elderly anyway). It looked like the only option I had was to ask a local volunteer group for help, but in all my life I have never had to turn to charity. I also didn't want a random food parcel from the council (which, as far as I can tell, are really intended for people in poverty rather than people like me who have enough money but just couldn't go outside). Fortunately I was able to get a Morrisons food parcel delivered which wasn't great but did the job.
My sister's experience was different, she was isolating due to her partner having symptoms. She had no problems with shopping as her friend lives next door. Her problem was financial, her employer gave her a choice between SSP or using annual leave. I suspect the employer could not afford to pay full wages when they had several staff isolating and had to pay other staff overtime to cover. These employees are key workers in the care sector so working from home or closing down were not options.
Someone else I know had to isolate, and was told by their employer that they would be paid on this occasion, but if it happened again they would not be paid. They said they were made to feel like a naughty child who's forged a note from his mum to get out of PE...
Some people simply cannot afford to lose their income, so will go out to work despite the need for isolation.
So overall, if we are asking people to isolate (and I assume Track and Trace will make this more common, possibly on multiple occasions), there needs to be practical and financial support. And this needs to be 'official' rather than relying on the kindness of volunteers and/or the compassion/ability of an employer to continue to pay wages.