Welcome to our forum.
It's undoubtedly true that top manufacturers sell thousands of tubs. But how many of those people come to this forum? I would argue that only a small portion actually participate (look at the user stats). However, it seems that more than just a few of these individuals DO have problems. Kinda makes you wonder about how many problems the people who are NOT participating have? Hmmm, the term "representative sample" comes to mind....
How can a spa leak or have other problems right out of the gate? Lots of possibilities. People make the spas and people aren't perfect. Loaded on a truck with a forklift, driven over rough interstates and off loaded with a forklift. Stored and then loaded on a trailer and driven to the customers home.