Is it just me that is annoyed/irked by this phenomenon?
Well, yes and no. ;-) My GF spent several years as an editor and I notice that she is irked (outraged is perhaps a better word) by typos, mis-spellings, problems with hyphenation or word usage that I just glance right over. (Like what I did there with "mis-spelling". Did that drive you nuts? It would make her scream in frustration. ;-)
I was pretty happy with my PHB (1st printing) though I felt that some of the smaller paperbacks I bought (Stronghold Builders Guide for instance) were obviously not edited as well. I figure thats just a matter of economics; WotC probably only has so much to spend on that book and paying for a lot of edit time isn't part of their plan. Oh well.
It's just laziness that results in so much error.
This I disagree with strongly. I've watched the edit process and if you want to do a good job you end up spending a lot of time. Its just not possible to catch every mistake the first time through. As far as I can tell, there are two major things that can go wrong:
1) Not enough time spent. I've seen things like freelance editors being called a week before a 200 page manual is supposed to go to blue-line and be asked to "give it a quick look over. We have 20 hours budgeted. Is that enough?"
2) Last minute changes. Someone in marketing thinks it would be cooler if the box said "50 Missions of Mech to Mech action!" but actually spells it "50 Missing of Mech to Mech action!". The editor never sees it until they've printed 120K boxes. Oh well.