Well, the EBS hasn’t existed since 1994. It was replaced by the EAS, the Emergency Alert System, a joint service of the Federal Emergency Management Agency, the National Weather Service, and the Federal Communications Commission. The EAS is intended to notify those resident in the area affected by an emergency. In 1997, the FCC eliminated the weekly on air tests you used to hear. Those tests were replaced by weekly internal tesing of the equipment, and monthly on-air tests. All radio stations are required to purchase and install the equipment as a condition of their licensing. I don’t know quite as much about the TV side, as I’ve never been involved in TV broadcasting, but I would think most if not all major stations are required to maintain the equipment.
The following two links give some more info on EAS. The second one is particularly cheery. Makes a great bedtime story for the kiddies.
http://www.fcc.gov/cgb/consumerfacts/eas.html
http://www.fema.gov/rrr/rep/easrep.shtm
As for the sirens question, it’s quite simple- they use both. Sirens for folks who aren’t listening to the radio or watching TV, and the EAS otherwise. Many tornado prone areas have upgraded their simple sirens to massive area loudspeakers, to broadcast details of the situation. Now, if they announce an emercency, the EAS broadcast goes on ALL radio stations in the target area. Once upon a time, I got to drive through a tornado system in Indiana. Sirens going, all the radio stations on EAS, it was a blast.
The EAS certainly isn’t a pork product- it’s really one of the most commendable and justifiable functions of government. Even though WWIII isn’t exactly right round the corner any more, tornados, earthquakes, ice storms, and nuclear/biological/chemical accidents more than justify the expense.
And if you have bad reception, switch to another station. It’s not like they’ll just be broadcasting on one… they want to save everyone, from classical listeners to howard stern fans.