You're correct, just about all "new" cassette decks contain Tanashin-originated components. Even reputable brands like Panasonic (National), TEAC, Son, Aldi & AllyExpress all use the same crappy mech.
Techmoan has been shown that nearly every "new" tape-playing device these days all contain the same lousy mech, some not even capable of stereo playback!
VWestlife covered the "world's first Bluetooth capable portable cassette player" which is a few years old now but also uses a lousy mech (mono!).
Cassette audio today seems to be more about the experience and social aspects of making, trading, and playing tapes ( Ala Guardians of the Galaxy style )rather than getting the best quality audio.
https://youtu.be/nezGOVOpHtc
https://youtu.be/WVylfRhIA7o