I too do not feel that this is a union issue. In one aspect, Paramedics choose to put themselves through the schooling necessary to perform the job and take a spot in a commercial ambulance agency for average pay. In another aspect, the oppertunity to be a civil service medic in this area is slim to non-existant.
We (north of NYC) have the luxury of having enough commercial ambulance agencies that it isn't necessary to hire municiple paramedics. This keeps the cost down, which keeps their pay minimal.
Consider a volunteer FD. If you can get people to volunteer their time, why spend money to pay people for it? In my opinion the same is true for EMS. If you can contract a commercial agency for a marginal cost as opposed to paying your own (mainly unionized) people much more for the same job, then why not?
I think it is an abomination that medics make as little as they do. Maybe the question isn't why is it so difficult to make a living as a medic, but how can we make medics more appreciated in order to earn a better living?