that is one of the industry problems,along with contractors failing to study a product to obtain a proper understanding of it,in order to install it properly. 
in a price conscious market these can be things "some contractors" do to try and break even,instead of trying to do the job with the best value for the customer,they do one at the lowest cost,a good contractor knows the difference,and would rather install a job that will withstand the test of time--unfortunately,all too often we are all tarred with the same brush,and have to "prove",we believe in doing a quality job,with good materials,