I don't know anything about strap construction, but I do have a ton of experience with lifting straps working in mines across the USA. Safety standards here are very strict. We could only use certified straps for lifting, and if they had grease on them or any frayed threads we were not suppose to use them.
The slings we buy here in the USA have a tag with their lifting ratings based on how they are used (straight, basket, choked).
I don't know about tow straps, but I bet there would be a ton of hoops to jump through to manufacture and sell lifting straps.
Here is one regulatory agencies policy on slings - OSHA - is a major workplace safety organization in the USA that regulates working conditions.
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9834