Well let's be clear about the tech they use. It's too slow to dynamically change based on who is shopping. The labels typically use eReader type displays which only update periodically for price updates. Need a 2450 cell battery that can last about 6 months with a single price change a week. Changing the prices more often drastically drains the battery life. And they require constant vigilance to make sure they haven't just randomly turned themselves off (seriously sometimes they randomly forget what price they should be showing).

I guess what I'm saying is if you want to ruin one of these stores those labels are expensive as fuck so bring a small jewelry kits and destroy as many as you can to fucking ruin a stores bottom line because no way in hell head office will approve sending out another thousand labels so they'll be forced to go back to paper labels.