Why the Weather Forecast Services in South Texas do not include the UV levels in their reports

In Mexico the National Weather Service does this on daily basis. Southern US States receive similar sun radiation levels.

The UV index of any given city is usually available from multiple sources, such as TWC or wunderground. As far as the NWS, that is likely up to the lead meteorologist of each Forecast Office, as to if, where, and how they make that information know.

If your having trouble locating it for your city, use the link below:

http://www.epa.gov/sunwise/uvindex.html

Edit: I should note that in the US, it isn't the National Weather Service that hold the primary responsibility of monitoring the UV level- it's the US Environmental Protection Agency.