Why don't kids offer to do chores for neighbors anymore like mowing lawns or shoveling snow?

Mine did. My youngest would walk dogs for the older neighbors who weren't able to take their dogs to the park.

My oldest did yard work for those same neighbors.

Oldest is now a university graduate and youngest is in his second year at university. 

Helicopter parents won't let their kids go outside to do these things, because they are afraid they will be attacked/kidnapped by the neighbors or hurt themselves doing the good deeds.

they are to busy sitting on their rear ends texting or playing games on the computer

They all get too much pocket-money.

They do.  Perhaps you're just a mean person.