I've been doing research to find cars with neon or ccfl lights. I just found out that the BMW Z8 tail lights and turn indicators are neon. Apparently, BMW claims that the neon tubing would last as long as the car itself.

It is the same claim as was done with HID front lights and also with all the LED lights.
And it is the same claim as "the transmission oil has lifetime over the whole car life so it does not be changed".
But in realty their definition of "car lifetime" is it just barely survives the factory warranty...

You are too harsh with these. While HID headlights may have a limited life, properly filled neons may really last into tens of thousands hours, that's more than enough for the life of typical car.

I have a car neon aux stop light, German made by Hella, from the times 'before LEDs'
Probably worth of posting a picture here. A thin custom neon tube with quite sophisticated driver circuit in use.

1997-1998 Lincoln Mark VIII

You are too harsh with these. While HID headlights may have a limited life, properly filled neons may really last into tens of thousands hours, that's more than enough for the life of typical car.

From that metrics the LED's should have really unlimited life, order of magnitude longer than the car. And for most functions incandescents could be designed to have "way longer then the car" lifetime as well, at the expense of the power requirements.
The problem is, the cold cathode discharges require extra complex circuitry within the light, which in theory should have unlimited life too, but in real life it gets extremely easily damaged, mainly by the humidity. Cause could be even a small break in the light assembly casing, allowing moisture in. And the problem is, the materials normally used for these casings just has limited life and are getting brittle pretty fast.
And then the cold cathode discharges suffer the most, because they need high voltage supply there, which makes the electronics really extremely sensitive to even very small amount of moisture ingress.