The issue is, the average customer has little to no idea about notifying building control and zero clue about what paperwork they should be getting from us.
If they general public were properly clued up, it may help but there will always be those willing to forgo a little paperwork to save a few quid.
It's an admirable idea but it's simply not possible to align all sparks pricing because everyone's circumstances are different. Consider an example...
A client has asked me to change 6 light fittings. I know there are no issues that require attention on the circuit because I've already inspected the property as part of my repairs that were required following a small electrical fire. How long would you quote for that task?