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The recent increase in gear ratios in automatic transmissions is designed with fuel economy in mind.
Most manual transmissions available from the factory in small cars in the US in recent history are not designed with economy as the most important element; instead they are geared for performance or for cost. The manuals are either the “cheap” option or the “sport” option. They don’t have a wide enough spread between first and last gear, so the designers have to choose between performance and economy. So they put a low final drive in the car, and let the RPMs suffer at higher speeds.
Just as an example, the reason my car has the gearing it has is that you can go exactly 60mph in second gear at redline of 7800RPM. Thus when they advertise 0-60 times they have the lowest possible gearing to maximize acceleration while only needing to shift gears one time.
The “solution” is to put a lower first gear, taller overdrive gear, and a middle of the road rear end gear in the car, which nets you the best of all worlds. The downside is that now you have to increase the physical size of the transmission to fit these larger gears, the stresses on the gears are higher, and you end up with a much more expensive transmission that consumers today aren’t willing to pay for. Imagine a world where the manual is a more expensive option than the automatic, that would cut out all the “cheap” sales and leave just the “sport” sales.
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