Should V brakes be able to lock the front wheel?
Regarding locking the front wheel, they are sort of correct: on paved surfaces and tires with decent grip the rear wheel should lift off the ground before front wheel locks. 

However, it sounds like you can't lift the rear wheel either. A decent set of brake pads should last much longer than 200 miles and brakes should not be adjusted every week (unless you ride 2000 miles in a week), so it's probably best to switch to a different shop. It might also be that the brakes are just garbage and could be replaced with a better set. As mentioned in a comment, a brake booster arch might also help.