you're wrong. Sorry.

No u. Bam, same level argument right there. Are you going to explain why or just throw out contrarian comments?

Cost will not be a limiting factor. Just about every feature on a 2023 car already costs more than a 1993 car's version. Did adding a wheelspeed sensor, electronic 4-channel hydraulic brake actuator, and dedicated ecm programming cost too much to implement ABS? Did the complication of 40 sensors (100+ now) and a voodoo box of electronics cost too much to go efi instead of carbs? Did the price of disc brakes stop most cars from ditching rear drums? Did the cost of engineering and testing prevent manufacturers from implementing the following nearly-negligible aero improvements to eek out another 0.1% of fuel efficiency;

1. aero strakes into mirror shells (prius, escape)

2. relaminating roof spoilers into every hatchback/suv and even into every pickup bed

3. Vortex generators on the top surface of tail lights (sonata, chr)

4. Active grille shutters (fusion)

5. Full underbody trays

6. Chin spoilers (splitters) on just about every car to keep air out from underneath

7. Hood beak splitters to keep grille air off the canopy (Volvo, accord)

8. Short antennas/glass-embedded antennas to reduce antenna drag

9. Front fender outlet vents to create laminar flow over the wheels (f150 2015+)

No, it didn't.

And I'd be interested to hear why you think helical-cut gears will be "noisy". I'm guessing you don't know why reverse whines in certain cars but not the forward gears

Edit: also, seriously, go do some shopping. LSDs are on the decline. On top of never being common in the first place, manufacturers at removing to brake-based simulated LSD rather than discrete components. There are incredibly few Fwd cars that ever had LSDs and fwd obviously makes up the majority of North American sales. Even Miatas and Mustangs only get LSD with optional packages.