The issue is that software is so layered, so you cannot guarantee much if the foundations are not solid. It's like as if a building is being built by different

The issue is that software is so layered, so you cannot guarantee much if the foundations are not solid. It's like as if a building is being built by different companies, most of them having to create a generic enough solution for other companies to be able to build just about anything on. That creates a tremendous amount of complexity. But that's true for many other manufactured items as well, and the manufacturer of the product that ends up in the hand of the customer ends up assuming most of the responsibility, since they had the opportunity to test the product fully assembled.