This seems to be quite a simple fix; SMS spoofing's a much more complicated problem I think because it requires co-operation across carriers.

There are also a lot of services which rely on "legitimate spoofing" e.g. skype allowing you to send text messages from it's service which appear to be from your actual mobile number (so they can be replied to etc).

It's complicated, so fast is the last thing you want --- unless you're happy with a high risk of inadvertently introducing new loopholes.

Currently they are doing nothing. So I stand corrected. Faster than 0mph.

I agree it needs fixing, and that the phone companies should try to fix it. Just not in haste.

It's a feature, not a bug.