That's why making each message costly is the way to go - it's not discriminating on what or how sent the message, it just forces sending to scale no faster than

That's why making each message costly is the way to go - it's not discriminating on what or how sent the message, it just forces sending to scale no faster than actual service of the business. A text or two per delivery or a doctors' visit is still a rounding error compared to costs of the transaction itself, but casually spamming hundreds of thousands of people becomes a noticeable cost.