I only have the LLC because I do other work, many types, besides mystery shopping. I would consider the threshold of having an LLC would be maybe $50k in independent contractor work where you use your car, interact with others physically (as in the gas station example) and have to swear to things (even the "I've no affiliation with 5 Guys" statement). My car, that I use for I.C. work, belongs to my company; not to me. I have my own car also or I wouldn't be able to write off the work car.
Schedulers/Companies share your information, it's in many of your contracts unless you opt out and many Schedulers are independent contractor's themselves who have access to our info and they, themselves, earn just a little more than us.
There's a zillion youtube videos of different ways to handle I.C. work and they talk about how the amount of money you're making relates to the types of reporting that are the most advantageous.