None of this is an excuse for this extremely bad decision to ship it in the 1st place. It wasn't even shipped as a beta product, but as a full-blown replacement for a fully functional app that people rely on every day.
Whether or not it is a bad decision depends really on what the overall objective is. See my reply to Elmer.
I know it sounds a bit over-dramatic but people are being directed up one-way streets, onto non-existent streets, illegal turns etc. This could be problematic especially at night when you might realize the error too late - yes someone can actually get hurt or killed.
Yes, you are being overdramatic, but people tend to be when they're talking about Apple. The fact is that GPS navigation systems have been giving duff advice for years, and yes, sometimes that advice has proven fatal. However, these systems were never intended to replace good judgement and common sense. In other words, if you let your satnav guide you over a cliff then you're an idiot. Bing once guided me to a gate that said 'track not suitable for cars'. Did I drive through it? No, I used the signposts to find an alternative route.
And I don't buy the 99% claim at all. Did Apple calculate how much of the data is actually valid? No of course not, how could they? When they released it I'm sure they were convinced it was 99.999% accurate.
Apple's data is taken and amalgamated from different sources world wide. Apple then does some jiggery-pokery to present a consistent(?) global service. The problem could possibly lie with the jigging or the poking, rather than the data itself. Some of the sources come from services such as Yelp which may also have local inaccuracies (I've already moved our local petrol station about a mile down the road). By now, Apple probably has about a billion search hits on their mapping service, along with requests for alternatives searches, and bug reports made directly from the application. They also ran it as a beta trial for a while and so I think they have enough information to make a fairly decent guess.
What really gets me is how Apple essentially admitted Maps is a failure and people should be using competing products, yet you still find Apple fans claiming it isn't that bad or that people are over-reacting. Which part of "Apple just admitted it is a POS" don't they get?
Because Apple fans understand something that you don't: the internet is the world's biggest echo chamber. You've got a number of factors affecting the problem's perceived size:
The number of people who genuinely have a problem (hard to quantify without access to Apple's figures)
The number of people who don't have a problem, but hate Apple (quite large)
The number of people who love Apple but hate Tim Cook for not being Steve Jobs (larger than group 2)
The number of people who don't have a problem, don't hate Apple, don't hate Tim Cook, but feel left out if they don't join in (I actually read a post from someone who said he didn't actually have a problem, but felt that he should because he read lots of other people were).
The number of articles repeating the same anecdotes from groups 1 through 5
Finally, the number of people who are using the service, don't have any issues, and so, quite rightly, don't say anything. (Size unknown).
The interesting thing that happened after the apology was the number of people now saying that the service is fine and Cook is a weakling for apologising! Damed if you do...