I used to work for a primarily-hardware company, writing software, and we suffered from much the same politics and software quality problems you describe. There are really two issues at play:

1) Hardware companies have to employ the waterfall model. Agile is not even a word in their vocabulary. This is because once a product is on the shelves or in the customers' hands, it is infinitely more expensive to recall and fix products. When all you have is the waterfall hammer, everything looks like a nail.

2) Culture plays a huge part. Senior management "knows best" despite your best efforts to convince them otherwise.

My boss once described it as "a huge ship that sails down the river. Once the ship is on its way, it is really hard to change direction or stop it".