Calica
and their staff isn't big enough to allow for someone to check all the books for inconsistencies. I think the problem is that these companies are putting out so many books, but they probably don't have a large enough staff to cover everything, so stupid mistakes and typos will be made.
These are huge companies we're talking about. And honestly, they get $10 a book! That's compared to the $3-5 in Japan. They should have plenty of staff for something like a proofreader. If not, they need to get some, 'cause it can really annoy you that unpaid groups scanlating for free do a better job than the ones getting paid.
Okay, long rant over. Phew.