I wouldn't count on that saving them. Plenty of independent publishers are run by former teachers. Many large publishers employ droves of former teachers. Yet there are lawsuits between industry players all the time.
TPT is able to sell lesson plans at extremely low prices, in large part, because they're not burdened with the task of identifying and paying rights holders.
I'm close friends with an independent book packager. Literally one woman who works from home, packaging book ideas. Book packaging means taking a manuscript from an author, building a book design, and sourcing/creating the associated media (images and illustrations) that make up the book. The only staff she employs (part-time) is dedicated to identifying and obtaining images for her books.
It's a surprisingly difficult task. You can't just perform a Google Image search for a topic, because the site you land on is rarely the rights holder of the image. You end up chasing a rabbit down the hole. She ends up using sites like Getty. While their pricing might seem ridiculous, it's a lot less expensive than dumping hours in to tracking down and negotiating with the person whose photo you found in a Google Image search.
It's easy to see TPT as this awesome, disruptive, middle-man slaying startup, but it's also easy to see how they're not playing by the same set of rules as everyone else. Maybe the rules are wrong. I'm open to hearing that argument. However, I am certain of one thing: it is not OK to hold people like my book packager friend to one standard while TPT is held to another.
