The purpose of uniform numbers is to provide different identification to tell players apart. These (9 and 09) may be mathmatically equal, but they certainly aren't identical when used as identification.
ASA made the change several years ago to allow this, for the reason stated.
ACTIVE is the leader in online event registrations from 5k running races and marathons to softball leagues and local events. ACTIVE also makes it easy to learn and prepare for all the things you love to do with expert resources, training plans and fitness calculators.