They are trying in the US as well but most the apps are garbage and no one uses them. Uber (and Lyft) are ubiquitous now and I think there would be a much higher adoption rate if they licensed it. Most companies also do not want to be in app development, if you could just buy software that works and focus on the core of your business companies would be much happier. This happens in giant enterprise-y businesses today. They consistently overpay on software that just works and lets them get along with their actual work.

But as I mentioned above the taxi industry is only the first immediate one I'd tackle, there are plenty others.