Because it will be obvious that it was modified, even to journalists, the public and a jury of your peers. Also the cops, who will arrest you for it.
But there is no such visibility for software.
> But there is no such visibility for software
Software modification has a lot of visibility, especially since Teslas log everything - why not log when new firmware was loaded? They could also checksum post-facto, but even that is not necessary: Tesla could implement something similar to Androids "fastboot oem unlock" option
What I mean by visibility is that you can't fudge it, that reality is plainly visible to all actors.
Income is not visible directly (although what one's house looks like for example is visible and is a good indication of income). If you meet a well-dressed guy in a Starbucks, you have no idea whether he's crippled with debt or whether he has so much money he doesn't know what to do with. And that's true regardless of the fact that income is regulated by the government, that banks keep records and all that.
Software is NOT visible in that sense: whether your microwave is running code that will make it explode when you type in 9999 or not, is not something that can be known by everyone but the first person who has access to the device, let alone the public who couldn't understand how to compare two hashes anyway.
As far as any third party is concerned, Tesla could just be faking logs and no one would know. Actually, you may not see it still, so imagine that say, GM, suddenly releases an autonomous car and it crashes. Do you trust them when they tell you that the logs say the driver was at fault?