A lot of Tuya Zigbee devices use Tuya specific clusters, so there is no native support for these in any home automation platform (except Tuya own Zigbee hub), until a custom driver is written for it.
I wouldn't say SmartThings has better support than HE for Tuya devices, probably the only exception is the above-mentioned possibility ST to handle remote dimmers broadcast packets (StepUp/Step Down).
Technically, this is what we are talking about:
I am not aware of any other Tuya devices that are supported by SmartThings, but not in HE. If such devices are found, it can be easily corrected 
The only exception are functionalities related to these inbound group messages.
