Because law enforcement and firefighters actually do work that help society and make us a safer and better place.

How many firefighters have you ever seen groping grandma's breasts?

In all seriousness, with the problems we already see with TSOs today-- attitude problems, not knowing the rules, making things up as they go along "just for the heck of it", and more-- we don't need a union. Unionizing them will only make it harder to get rid of the 80-some-odd percent who are poor or underperforming at their jobs.

Obama only supports unionization because it will add to the coffers of those who are some of his biggest supporters (unions and union bosses), who will likely use at least some of the additional dues money in a legally questionable manner.