Dear Mary: I’ve just discovered that my parents are being discriminated against because they don’t have a credit card. It’s a huge injustice if you discriminate due to color, race or religion, and this is totally unacceptable in our society. If you don’t own a credit card, you are not allowed to get a rental car; you cannot fly on an airplane; and I’m sure there are more issues of this nature that I just haven’t uncovered yet. Cash is not an option with these services. Isn’t this unacceptable? — Jonathan W. Dear Jonathan: I understand your frustration. It does seem unfair that some companies these days are averse to cash. However, I don’t think this is a matter of civil rights. Credit, like driving a car or owning a home, is a privilege, not an entitlement. The same goes for air travel and car rental. Those are not rights …