One reason is demographics. Another reason is government policy. Wherever they live, young adults, single people, Hispanics, and non-citizens tend to remain uninsured in higher proportions than the overall population. The NCPA study shows that Texas has greater numbers of each than most other states. Fifty percent of the uninsured are Hispanic.
Government policy is the other reason.
Lack of insurance is not a major barrier to health care. There are more than 40 federal health care programs that fund health services for the uninsured in Texas, and Texas counties are required by state law to have programs to serve the medically indigent. In Texas, there are approximately 1.6 million people eligible for Medicaid who are not enrolled. Those who are signed up for government insurance do not get more care, faster care or better care. Once you understand the statistics, you can begin to see the current circumstances and begin to design policies to deal with the problem.