Seriously going to try to say the ST speakers are equal in sound quality to the VT? Have you read the comments of the owners of these two displays?
No one disputes the the ST is a great value, but every reputable review states the VT and ZT outperform the ST - you just have to decide if that difference is worth the premium. For some of yes and others no.
There is no perfect display, quit looking for faults and enjoy
LG B7 OLED 65" (waiting for cal by DNice)
Ascend's with RAAL, Love my PSA v1800 and a 7.2.4 speaker config, Oppo 203 and other toys