Jamming wifi is easier than jamming cell towers. Most modern wifi operate on 2.4ghz and 5ghz. There are a lot of comsumer devices like microwaves that can interfere with 2.4ghz wifi signals. Even a green leafy tree can degrade a signal enough to cause connection problems. 5ghz is a bit tougher,but is possible.

When it comes to Charter, who knows. My Charter connections gets disrupted at least 3 times a week. The tech support always claim its my equipment. Bullcrap! So if Charter/Time Warner gets ask by law enforcement to disconnect an area, chances are that area already has connection issues.