Without that information, it seems kind of silly seeing everyone proclaim how Tesla is done because of this... It's like telling your doctor that you don't want the medicine because the better solution is to just never get sick in the first place... yeah, everyone agrees, but you are sick, so here take this.
I imagine that it's significantly cheaper to fix the problem (and identify a root cause) when the car is still in pieces than to disassemble the finished product to fix the problem.
As for re-tooling, that can be done down the line with a manual fix in place in the short term (after all, they're able to fix it manually after the assembly line is completed).
Much like how in software development it's cheaper and faster to fix a bug caught in development than it is in production.
Now software is different than cars, but I'm gonna say that I'd go for the latter just about every time. Both as a developer, and as a user.
Isn't swapping FPY for # delivered while they determine the root of the issue and fix it a good plan? It keeps the money flowing in, it helps them find other issues in parallel, and keeps cars getting delivered.
I see a lot of people critisizing Tesla here, but my question is what would you do? You are already in a situation where your plant is producing cars with flaws, no pretending that you don't make mistakes or are infallible and would never be there.
Garbage is flying off the line, what is the solution that you would go with that is better than what Tesla is currently doing?