A coalition of private interstate bus companies is filing a federal lawsuit Monday alleging New York City unfairly hit them with a blizzard of tickets under the Big Apple’s “bounty hunter” idling law to curb pollution. The American Bus Association contends that the idling law violates bus operators’ constitutional protections by imposing fines on their buses while exempting government vehicles such as MTA buses from enforcement, thus treating similar modes of transportation “unequally.” According to the complaint obtained by The Post, private carriers have received more than 4,000 idling summonses since 2020, resulting in hundreds of thousands of dollars in fines and mounting legal costs. The Hampton Jitney waits for passengers on the Upper East Side amid the coronavirus pandemic on April 08, 2021 in New York City.…