It's hard to quantify this data to make it into something meaningful.
You definitely need number of miles, and months of ownership to see problems per number of miles.
There are also some things that are just in the nature of a given car, and while those things might get reduced they tend to always pop up. Like I strongly believe the Model S will always have issues with squeaks and rattles. Partly because of the design. but also because it's so quiet. My initial service visit was mostly to fix them which the visit did go a long ways to fixing them. Did they fix all of them? No. But, its to a point where it doesn't really bug me. It's also sometimes really difficult to reproduce. On a previous car (a Porsche Cayman S) I gave up on it ever being rattle free. The suspension was pretty hard riding, and eventually given enough bumps it would rattle again. With the Tesla I've more or less accepted it will always be worse than what I want, but not bad enough to drive me crazy (like the Porsche because it was always the headliner).
The DU issues will also always plague Tesla, and not because there is anything wrong with it necessarily. But, because multiple issues are combined into one and labeled as a DU issue. It could simply be that it's making more noise than usual so it could be cosmetic in nature. It's still a problem and something that they have to fix. But, it's way different than something breaking which does happen with the DU's.
I'm at the 6 Month mark with 15K miles on a 2015 70D, and my car is performing nominally with no significant mechanical/hardware issues. It's not any better or worse than the majority of cars I've had at the 6 month mark. The only thing remarkably different is that it somehow has 15K miles on it. How that happened is beyond me. I think the problem exist between the seat and the steering wheel, and can't be corrected with a SC visit.
In terms of SW and glitches the Tesla is on par with a Range Rover Sport I had. Sometimes on that car I'd lose any speaker output. The only way to fix it was to get out of the car, lock it, unlock it and then get back in.
The Tesla has it's own set of hoops to go through when SW glitches happen. Owning the car is a lot like owning a computer. Sometimes you just have to reboot, but the car has multiple systems and ways to reboot. So it's not always straight forwards.
The other thing unique to the Tesla is someone at Tesla had the bright idea to have superchargers at the SC. This is absolutely brilliant because time to time things pop up. Like maybe we have a question about something, or we want someone to look at something real fast. Other times there are things like the Seat Belt inspection. For that I didn't even have to schedule a trip to the SC because while on a trip I happened to stumble upon a SC/Supercharger combo and some Employee at the SC did the inspection while I was charging. I didn't even ask. What I did ask for (Touch up paint) they didn't have.
Oh, and yeah depending on the Color choice they might or might not have Touch up paint. It's so funny that we go on and on about DU's, rattles, etc but the one thing that actually happens is they don't carry Touch up paint for all the colors they sell. Tesla gets the absolutely easiest things wrong. Like the Tesla Store one would think would be pretty easy to run, and to maintain accurate inventory, but that isn't the case at all. It's a buy and pray experience.
Will they have it in stock when you order it?
Will it actually ship? or will they email telling you they don't really have it
Will the item function as advertised?
Will the item follow the warranty of the car you're buying it for, or will it be separate? The answer to this depends on how you order it so be careful when ordering the HPWC
Will the item end up being kinda crappy only to be eventually dumped/redesigned. Like the tire chains (dumped), or the floor mats (redesigned)
Will talking about the item and the promises Tesla made go on and on within the TMC forum like the Center console fiasco was.