Is Ageism Affecting Businesses?

Recently, I have notice that an issue I have been facing more often than I would like to is ageism.  My mother (a former high school teacher), frequently vocalizes her opinion on the treatment of teenagers, and she asked me to try an experiment: to go into a jewelry store in the mall with her and note the attention we receive from the store clerk, and later on go in by myself and observe if the clerk's attitude toward me as a customer had changed.  As we predicted, it had.  When I went in with my mom, the clerk was very polite, asked to help us, and when we said no thank you, she left us alone.  However, when I went in by myself, I was not asked if I needed assistance, and instead was hovered over for my entire walk through the store.  Firstly, it was a jewelry store - everything was in locked cases, so how could I steal anything?  Secondly, I found the lack of trust and service to be somewhat appalling - how do they know I don't have enough money to buy anything?  This could have happened due to coincidence, but an unfortunate truth is that a lot of store managers train their employees to be cautious of teenagers, as they are "most likely" to shop lift.  I know that after my experience at that store I am reluctant to return, and I wonder if this is the case for many other teens?  I also wonder: if it is the case, and many others feel the way I do, and will stop shopping at the stores in question, how will this affect their business? I work for Safeway, and they instruct us to watch out for shop lifters of all ages; I am thankful that I am not employed by a company who exercises such biased opinions.