One of the things about Dallas is that you are looking at the Dallas AREA (DFW to some) not just the City of Dallas. With Houston, since Houston is so much larger than its suburbs, its not really comparable to DFW in terms of how growth and urban issues are handled. In fact, it is probably more like New Orleans in that way...

Part of what I think people see in terms of similarities between Houston and New Orleans (aside from the Louisiana transplants) are the effects of weaker or non-existent suburbs as seen in Houston and New Orleans. Dallas has many more larger municipal governments that focus their attention on smaller areas. Houston and New Orleans are the respective 800 lb. gorillas in their areas. The "competition" between cities in those two areas is limited and Dallas does not see the demands on services that a Houston or New Orleans does because it has several relatively strong neighbors.

Take a look at these lists:
DFW Area (6,817,483)
13 Cities with 100,000 — 1,000,000+ inhabitants
Dallas (1,207,420)
Fort Worth (757,810)
Arlington (365,860)
Plano (261,900)
Garland (228,060)
Irving (218,850)
Grand Prairie (176,980)
Mesquite (139,950)
McKinney (136,180)
Frisco (125,500)
Carrollton (121,150)
Denton (115,810)
Richardson (100,450)
51 Cities with 10,000 to 99,999 inhabitants

Houston area (6,371,677))
1 City with more than 2,000,000 inhabitants
Houston (2,160,821)
2 Cities with 100,000 to 1,999,999 inhabitants
Pasadena (149,043)
Pearland (106,500)
29 Cities with 10,000 to 99,999 inhabitants

New Orleans area (1,167,764)
1 City with more than 300,000 inhabitants
New Orleans (369,250)
2 Cities with over 50,000 inhabitants
Kenner (66,702)
Metairie, unincorporated (138,481)
18 Cities/Places with 10,000 - 50,000 inhabitants