Why buy a fare card for light rail train in Baltimore?

I recently took a round-trip from Thurgood Marshall airport to downtown Baltimore. I bought a fare card but at no point was there anyone or any machine who collected it from me. Does the MTA operate on the honor system?

No honor system exists on the MTA - random fare inspections are performed - in light of recent security incidents on the light rail. If found without a valid fare, you will be asked to leave the train and buy a fare at the next station. You could be arrested and pay up to a $525 fine if convicted.

Thank you very much and enjoy traveling on the MTA. http://answers.yahoo.com/question/accuse_write?qid=20061204143315AAdCmBL&kid=RcEpCDO7UmaIZOnoFEoVjgjitKPcc8TTeb4DJNyPm8SY4jk8Ggyg&s=comm&date=2006-12-07+08%3A13%3A35&.crumb=