Another argument is to not fuse the data. Just keep it as a backup decision maker akin to how Aviation systems are designed. If both systems agree, then you have additional reliability. Would love to hear from someone who's worked on these kinds of FSD systems.
Andrej covered this in a previous talk. If both systems agree, then nothing would be different if you did not have the 2nd system. If the systems do not agree then you ultimately still have to pick one in most scenarios.
IE if you are travelling down the highway at 80mph with a car close behind and your lidar+radar system says there's an immediate obstacle but your vision system says it's an overpass, do you emergency brake?
This goes for lidar and the interior, is simply what the believe the right solution is.
If they could save 100$ per car and have a traditional interior, I don't think they would do it.
The same for lidar, even if it was free, they wouldn't use it. They simply believe the additional complexity of sensor fusion is not worth it.
In regards to LIDAR - I think it's possible to drive safely without depth perception. One eyed humans do it just fine. It may not make sense to have LIDAR on every single machine you want to have vision processing with, including the Tesla bot. So it makes sense to solve problems without using it.
Tesla's main goal is to do a lot while keeping the costs low. The fact the the entire interior is devoid of critical things like buttons is a testament to not how they're good at UX/UI, but how they've shaved off $$$. Pretty impressive. A potpourri of features in a Tesla car are all software-based (fixed NRE cost, essentially zero bloat on the COGS). Spending extra on a set of buttons, let alone a LIDAR system, would piss off the bean counters. If anything else, their marketing is great and people love the brand (and the stock).