It's Time for Tougher Scrutiny, Many Subway Riders Concede
New York City subway riders view tougher scrutiny as inevitable next step in series of heightened security measures following 9/11 attacks and latest bombings in London; some view prospect of being stopped by police as just another nuisance, while others doubt police assurances that searches would be random; some say they fear unequal treatment for riders based on race or national origin; array of bags, boxes and packages that are routinely carried on and off subways seems certain to complicate logistical questions faced by police; searches seem certain to lead to criticism, if not legal challanges, from civil rights advocates in city; photo (M)
