It's difficult not to be cynical about editing (or lack thereof) errors. Since publishers are facing immense decreases in their physical publishing products (i.e. pBooks), they are looking to retain their profits by maintaining the same high prices on eBooks, which cost much less to produce (no paper, printing presses, bindings, transportation, shelf-space, etc.) and add to those profits by firing proofreaders.
On an off-topic observation/opinion, I think much of the unemployment we are seeing in the U.S. and abroad is due to the continued increase in such automation, mechanization and computerization of tasks formerly performed by conscientious workers.
But I digress ...