That certainly hasn't been my experience. Most pharmacies I've tried this with need to actually 'fill' the script and run it through insurance to get a final price. And, in the era of 'COVID-related staffing shortages', good luck calling the pharmacy and actually getting someone on the line.
The sad thing is, all these pharmacies know about GoodRx and other discount providers. They could stop playing games and just run all scripts through these providers to get a 'cash price', but they don't. It's honestly like shopping at Kohls where if you aren't stacking coupons, you're the sucker paying too much.
I don't know about Cuban's mechanics here, but a website that shows you the final price, no games/codes, is a great addition to the market.