I saw that Pete Townsend has donated his synths to a school in West London.
That includes a Yamaha GX-1 and an EMS modular. That’s some of the rarest (and largest) synths ever made and would have cost the equivalent of hundreds of thousands at that time.
Not too many muscle in the 1970s would have been able to buy a GX-1.
The comparison is more like bulldozer vs. car than BMW vs. Toyota - entirely new capabilities are unlocked
Most polyphonic synths use individual chips for the main building blocks such as voltage-controlled oscillators, filters, and amplifiers, such as https://www.cabintechglobal.com/as3350-smt. Those are simple analog circuits, but the specific designs that work for synths are not really useful for anything else, so they are a boutique and expensive (relative to complexity) chip. Using those: N chips per voice x 49 keys x 3 voices per key = 147*N expensive chips.
There are also some "whole synth on a chip" available like https://www.cabintechglobal.com/as3394-smt at ~$10 each. So best case is ~$1.5k in chips alone for the core of this synth. Some other support circuits are still needed. Then $$$ for big PCBs and a big, noise-free linear power supply.
But even if we could drive the electronics costs down, that doesn't affect the per-unit cost of front panel controls, keybed, or the wood cabinet. Nor the per-unit cost of manufacturing labor, packaging, logistics. Nor the per-project cost of R&D and manufacturing tooling. All of these scale with size and complexity.
So it's no different from other specialized goods - the price gap relative to the "good enough" baseline will always be more than the performance gap suggests because the specialized version inherently sells fewer #units and cannot activate the same economies of scale.
But unfortunately, it will primarily be used by rich YouTube "creators" to recreate some old Jean-Michel Jarre tracks.