Surely the time a duty from standby at home starts depends on the type of standby your are on. If it is immediate then that is the time the duty day starts regardless of what time one chooses to get out of bed hours beforehand.
The airline I used to work for gave us standby's lasting a couple of weeks with time off on some nights.The minimum amount of time we could be called from standby varied from days to day. Max 24 hours notice down to 90 minutes notice or immediate at or near the airport. If I was selected for a duty from say 12 hours notice my starting time would be the normal reporting time at the airport, not 12 hours earlier.
If the standby is from airport standby then the time one starts the standby is the time the duty starts. If someone was selected from standby after spending 5 hours 59 minute on standby then the maximum duty they could perform is about 6 hours depending on the airline. the time the standby was started and the amount of sectors for short range flying. Obviously airport standby's starting before 0559 would be far more restrictive and could only be a short duty.
I cannot calculate the long days amounting to 20+ hours that some people have come up with.
If people want to live more than 60 minutes driving time from their airline base then they should accept that every working days is going to be a longer day than it would be if they lived closer to their base. I realise of course that some people have to live where they do for reasons relating to their private lives.