If you are implying shops repurpose old beans and use them to make cold-brew, then you are correct.
I can't speak for all coffee shops, but for 'specialty' places the above statements are always true.
> Taste wise, it's completely subjective
True, but the taste profiles are objectively different.
Grilled chicken vs roast chicken. Which one is better? Subjective. Do they taste different? Objective.
That being said, I am going to try this aeropressing onto an ice cube method.
Does aeropress allow you to use cold water?
My general approach is: ~2.5 scoops into the aeropress, fill with 165 F to just above the -2- marker, stir a few times, immediately press out over 20 seconds directly onto tumbler of ice.
BTW, if you want your coffee slightly sweetened, you can put a tsp of sugar into the aeropress with the grinds and press the combination over ice. Saves needing a simple syrup or having the sugar not dissolve if you put it into the iced coffee afterwards.
This is of course very similar to how vietnamese iced coffee is made. https://ineedcoffee.com/brew-vietnamese-coffee/
I think cold brew is an attempt by coffee shops to upsell what used to be regular coffee + ice. Taste wise, it's completely subjective. Value wise, nothing beats Starbucks double shot on ice.
At home, I just aeropress into an ice cube. That way, I don't have a pitcher of cold brew concentrate that has to be used within a week.