Most phone plans in the U.S. include unlimited SMS/MMS messages, including prepaid MVNO plans that are very affordable (with entry-level plans under $20/month).

Most phone plans in the U.S. include unlimited SMS/MMS messages, including prepaid MVNO plans that are very affordable (with entry-level plans under $20/month). Pay-as-you-go plans are an exception, but they are becoming less cost-effective as monthly plans become more competitive. I think the consumer mindset changes as soon as something is advertised as "unlimited", because you no longer have to think about conserving resources.