Max Power said:
Unfortunately neither of these stadiums was built including the equipment to roll the field outside. The only teams that have stadiums with that technology are Arizona and Las Vegas. Houston's stadium is older so that makes sense, but when the stadium in Dallas was built it absolutely could have been included.
Seven teams from the NFL who normally play on turf had to have grass installed to host World Cup games. In addition to Dallas and Houston there was also Atlanta, New England, Kansas City, Los Angeles, and NY/NJ.
Either Reliant or Cowboys COULD have included it (Phoenix's stadium was built 3 years before Cowboys and there were at least 2 European stadiums with rolled in tray grass before or about the same time as Reliant), but it wasn't practical in either, especially Dallas. Phoenix has something like 3500+ hours of sun per year and the low temps rarely get into the 20s, and not many days in the 30s. DFW, on the other hand, is higher than average but is still quite a bit lower than Phoenix in terms of sun and winter lows get down, and stay down, far more here. Growing the field outside just isn't practical in Texas, even in Houston.
Besides, some don't like the Cardinals grass. They say it is too slick.