@djsundog I suspect some of it is also on the demand side. Percussion has a bajillion different instruments that each need to earn back their R&D while synths have all their engineering-heavy parts reused between models and change the default soundbank or case aesthetics.
@USBloveDog can't mass produce artisan handcrafted sound waves as inexpensively as some vibrating bit of quartz can, but you pay for quality, that is just simple acoustioeconomics.