Are you saying there is causality? GA in Europe (or lack thereof) and over regulation?
Yes. And not just GA. All facets of EASA regulated aviation.
Instead, compare the timeline to bring an autopilot (or engine) to market pre WWII, and what that effort looks like today.
No comparison. If you want to compare start in 1959 after the Chicago Convention and the formation of ICAO. Anything prior to that is meaningless. 75% of the FARs we have today are due to our commitments to the Convention, ICAO, and other agreements. It’s these common regulations that permit our aviation products and articles to move freely on a global basis. It’s also the reason items certified in various countries are automatically certified in other member countries. To use your Auto-Pilot example, what would be the added costs to have that auto-pilot certified in every country you wanted to sell it or fly with it in?
Sure, but I don't want to copy and paste all of Part 23 here.
Here I pasted it below. Not much left is there? Part 23 went through a massive rewrite a number of years ago. Majority of it was moved down into Advisory Circulars (FAA acceptable data) which allowed the use of consensus standards. Why you ask? To try and jump start new GA interest since the LSA attempt fizzled. So how many new aircraft have you heard of on the drawing boards in the last 5 or 6 years?
PART 23—AIRWORTHINESS STANDARDS: NORMAL CATEGORY AIRPLANES
Contents
§23.1457 Cockpit voice recorders.
§23.1459 Flight data recorders.
§23.1529 Instructions for continued airworthiness.
Subpart A—General
§23.2000 Applicability and definitions.
§23.2005 Certification of normal category airplanes.
§23.2010 Accepted means of compliance.
Subpart B—Flight
Performance
§23.2100 Weight and center of gravity.
§23.2105 Performance data.
§23.2110 Stall speed.
§23.2115 Takeoff performance.
§23.2120 Climb requirements.
§23.2125 Climb information.
§23.2130 Landing.
Flight Characteristics
§23.2135 Controllability.
§23.2140 Trim.
§23.2145 Stability.
§23.2150 Stall characteristics, stall warning, and spins.
§23.2155 Ground and water handling characteristics.
§23.2160 Vibration, buffeting, and high-speed characteristics.
§23.2165 Performance and flight characteristics requirements for flight in icing conditions.
Subpart C—Structures
§23.2200 Structural design envelope.
§23.2205 Interaction of systems and structures.
Structural Loads
§23.2210 Structural design loads.
§23.2215 Flight load conditions.
§23.2220 Ground and water load conditions.
§23.2225 Component loading conditions.
§23.2230 Limit and ultimate loads.
Structural Performance
§23.2235 Structural strength.
§23.2240 Structural durability.
§23.2245 Aeroelasticity.
Design
§23.2250 Design and construction principles.
§23.2255 Protection of structure.
§23.2260 Materials and processes.
§23.2265 Special factors of safety.
Structural Occupant Protection
§23.2270 Emergency conditions.
Subpart D—Design and Construction
§23.2300 Flight control systems.
§23.2305 Landing gear systems.
§23.2310 Buoyancy for seaplanes and amphibians.
Occupant System Design Protection
§23.2315 Means of egress and emergency exits.
§23.2320 Occupant physical environment.
Fire and High Energy Protection
§23.2325 Fire protection.
§23.2330 Fire protection in designated fire zones and adjacent areas.
§23.2335 Lightning protection.
Subpart E—Powerplant
§23.2400 Powerplant installation.
§23.2405 Automatic power or thrust control systems.
§23.2410 Powerplant installation hazard assessment.
§23.2415 Powerplant ice protection.
§23.2420 Reversing systems.
§23.2425 Powerplant operational characteristics.
§23.2430 Fuel systems.
§23.2435 Powerplant induction and exhaust systems.
§23.2440 Powerplant fire protection.
Subpart F—Equipment
§23.2500 Airplane level systems requirements.
§23.2505 Function and installation.
§23.2510 Equipment, systems, and installations.
§23.2515 Electrical and electronic system lightning protection.
§23.2520 High-intensity Radiated Fields (HIRF) protection.
§23.2525 System power generation, storage, and distribution.
§23.2530 External and cockpit lighting.
§23.2535 Safety equipment.
§23.2540 Flight in icing conditions.
§23.2545 Pressurized systems elements.
§23.2550 Equipment containing high-energy rotors.
Subpart G—Flightcrew Interface and Other Information
§23.2600 Flightcrew interface.
§23.2605 Installation and operation.
§23.2610 Instrument markings, control markings, and placards.
§23.2615 Flight, navigation, and powerplant instruments.
§23.2620 Airplane flight manual.