The issue is not about 1%, but one of the cost of hiring trades people. HVAC companies are charging $25k for a three-ton HVAC unit+furnace in California, when the cost of the the unit is 5k. And these trades people don't want to fix any problem instead they want to sell a full replacement. Same with electrical. You call for some issue. a banktrician (PE owned company with 60 month financial plan) comes and sells a full panel upgrade, full rewiring? What is going to happen then?
Any person with a decent STEM education can learn these trades for DIY'ing. They can learn safety protocols too. When HVAC/plumbing/electricals are installed in a way conducive to robots, it is easier for those who can't afford a lot of money, to work and fix these issues.
The world (esp in residential) is not a union of two disjoint sets: (a) robots/AI (b) trades people. In fact, the third world is huge: an average tinkerer without being burdened by gatekeepers of the trade can fix many issues when these installs happen. At least it becomes easy to replace parts by oneself, instead of hiring a technician.
Your average technician is no better than a tinkerer. For instance, look at HVAC symptoms: https://imgur.com/a/FXf3iXf That's what many HVAC techs carry, they even carry apps that just takes the inputs (pressures, temperatures, etc) and spew out what could be the cause. What if a HVAC system is built in such a way that it is easy to replace parts? Right now, to replace compressor, one has to discharge the refrigerant, unbraze suction and liquid lines, vaccum out, then use nitrogen, braze both lines, then charge it back. Can we have a world where it is easy to reduce these steps so that it becomes easier for robots (as well as for humans)
How about having universal VFD boards the way ABB sells VFDs for water pumps and other motors, instead of getting tied with a particular brand?
The real problem is whether average home owner can bear the cost of trades people? Sure, trades is just like Accenture IT consulting: one rock star software engineer with 30 dummies who can jack up the billable hours; same goes for law firms too.