I agree that work place and sports are not intended for "dating/romance", people are paid to work not flirt and date, and any hanky panky can divert people's attention from their primary function/purpose. There is time and place for everything. If two people meet in such places and want to have a relationship that's fine, but they need to take it outside, keep it professional while at work/sports facility.
But the rest of the "concerns" is nothing more than "moralizing" and subjective: age difference, ranks, teacher-student factor... It is possible that when two people meet, "student-teacher" or "boss-employee" or "19 and 35 year old", they might have found a true love, a life long partner, or! a nice affair, a great sexual experience, a fun one night stand... If they are consenting adults, who is to say they can not have a relationship outside of work/sports facility?
Also, when 2 people meet and there is an attraction, one of them has to make the first move... Of course such 'first move" must be done in a respectful form, and not repeated if rejected. Otherwise what's a problem, if one asks the other out on a date AFTER the working hours or training session?
If these two people end up getting married, then good for them. If they end up having a one night stand, even better, both had a fun evening or an afternoon... if they don't like being married - they'll divorce; if they don't like how the sex went, they won't do it again..... Who cares what their rank or age is (if they are consenting adults).....