SMS text message spam is barely a problem in the US and Europe. Certainly nothing like what some doom-mongers were predicting a few years ago. Operators are incented to control it to maximize customer satisfaction -- number portability has made customer churn a potential business killer.
In Europe, the economics of sending text messages are different from those in the US -- in most countries the sender pays, not the recipient. The US is unusual in this respect -- in the US, one can usually send an SMS by emailing to an SMS gateway. This is free of charge to the sender but paid for through the receipient's plan. In most other countries, sending access to the SMS network is restricted to those who have a financial arrangement set up with the carrier -- receipt of messages is free. This destroys the indiscriminate spammer's business model.