it's been suggested (by whom? I can't recall) that the tattooed woman is meant to show that time was changing and that things were getting more liberal. That such an unusual woman was out in daylight perhaps meant that the people in town were more accepting tof differences than Ennis feared. The fact that her partner is a black hat wearing man might even draw us to believe that Ennis and Jack could actually be out and about together without too much trouble. Thus making his fear all the more tragic, because it may have been possible to have that "sweet life" and be accepted. Just like the Black Hat and White Hat men in the bus station, suggest a possible alternate existence for the Ennis and Jack. I'm not sure I believe that entirely, but it's worth playing with, symbolically.