Like you say avoiding liability is in everyone’s interest. In a utopian libertarian society maybe an inspector someone you’d want to pay electively like an engineer.
Someone who could coordinate consultations with surrounding properties and engage others who are experts with say surface water etc.
The other option might be your insurance company would require inspection for you to receive coverage… In the event of say an HVAC electrical fire. Then the cost is certifying the build is covered by a private company instead of being a state operated service which is free from the pressures of competition. Also then delays in permitting could also incur liability :)
In reality if permitting is quick, affordable and isn’t weilded like a political weapon Im mostly fine with it. The federal government is using it to pretty much shut down oil and gas development in Canada. Municipal permitting is partly why we have a massive housing crisis.