There is nothing nefarious or stupid going on in the US. In most other countries in the world there is a separate area code for mobile phones. Calling a mobile phone area code is considerably more expensive than calling a land line (for the caller). To get an idea of the difference lookup rates for any international calling card. For example the first one I found charges 1c per minute to UK landlines and 5c per minute to UK cellular. For many countries there is a 1:10 difference in cost.
So now we have established that calls involving a cellular endpoint are more expensive virtually everywhere. In places that have a separate area code for cells it will be the caller paying the additional cost.
In the US (and elsewhere participating in the North American Numbering Plan) it would be virtually impossible to allocate new area codes, so there is no way of knowing the recipient is a cellular phone. The only practical way of dealing with this is to make the recipient pay the extra which is exactly what happens. But someone is always paying! And a lot of people don't mind this, especially when mobile service was new. If you were a plumber on the go you didn't want people to think about calling a competitor on a landline while you had a cell because it was more expensive. Having all calls cost the same significantly reduces friction for people who want to communicate.
Because the recipient is paying for incoming calls and that person is making the purchase of the incoming minutes there is very strong pricing competition. Incoming and outgoing minutes are relatively very cheap in the US. So much so that the carriers have to nickel and dime people on everything else in order to make up the necessary ARPU.
It should be feasibly possible. All the US carriers maintain email to SMS gateways, so with a sufficiently large amount of computers spamming one email address, you could cause some harm.
(This is how text messages work in the USA.)