Read the warranty book which comes with whatever new car you decide to replace your P5 with - You may not be covered any better with that one than you were with your Mazda.
All manufacturers know that there ARE folks out there who can break ANYTHING, no matter how well designed and built they make it, so they always put some clause in the warranty to protect them.
Mazda wasn't legally obligated to repair your first transmission, let alone your second. They did both as a gesture of good will, as they want all customers to be satisfied, but again, there are some folks you can never satisfy.
From the Protege 5 warranty booklet:
What is not covered
Factors Beyond the Manufacturers Control
"Misuse of the Mazda Vehicle such as driving over curbs, overloading,
racing, (my emphasis) snowplowing, etc."
My "hot rod" uncle had exactly your same experience with his first new car, nearly 40 years ago. He tore two transmissions out of it in less than 10,000 miles. They fixed the first one, and never said a word to him. They also fixed the second one, and told him that the next one would not be covered. He never broke it again. Maybe they fixed it "better than new" (unlikely) or maybe he "toned things down a bit" since he knew where the next repair was coming from

Only difference I can see, is that he never claimed the car or the transmission was defective, or that the dealership was screwing him - He KNEW what was wrong (and who was to blame) with his transmission, both times
Don