I personally find the almost absence of spam on WhatsApp a big success story for it. Think about how much Spam still hits your email inbox (and nobody knows how much is filtered away before it does).

I totally understand why they try and make it hard for integration to happen. When compared to classic SMS, the fact that you need to start a conversation with a preapproved template means that they have a way to control casual interactions.

Companies in spain use it for legitimate reasons, so its more a lack of usage which makes spam the only usage?

That seems a but pessimistic. A few companies use it for customer service, like ime Adidas Germany [0] (they handled an exchange for me once on there). It is effectively just another customer support line like a chat portal on a website.

[0]: https://www.adidas.de/en/help/contact-us