As a long-time former resident of inner-city Houston (the Hispanic area), there is a certain amount of crime in these areas, just not as much as in the black inner-city neighborhoods.
But there is also a good respect for law and order, especially among the US Hispanic citizens, less so among the illegals, but there is still some there (maybe fear of the law). Also, everyone in the Hispanic barrio owns a gun (New Year's Eve sounds like the American army invading Berlin). And there is a strong amount of private development going on.
In fact, Dallas and Houston are really the only two Texas cities with any inner-city black population. Could explain part of the difference (without wanting to sound sort of racist)
Yes it does, and I suspect frankly that San Antonio and El Paso have fewer illegals than many places. There simply is too much Hispanic competition already there, and there are more profitable areas for hard working illegals to mine willing to work for relatively low wages. Just a wild guess on my part.
I might add that the ghettos in LA are rapidly turing brown, and the most heavily black area of LA county is a middle to upper middle class area now (Baldwin Park and Ladera Heights).