I kinda feel like people are equating recoup costs as meaning you are selling it for outrageous prices. The way I'm reading it you really just mean recoup the cost of the alcohol

People are just taking her at her word. She said this:

we realized we could probably recoup some of our costs on the other wedding expenses by charging moderate prices for drinks

Doesn't leave much room for interpretation. Charging "moderate prices" means they're clearly not intending to charge at cost. Other wedding expenses means that their intent wasn't just to recoup the cost of the alcohol, but to make a profit to cover the money they spent on the wedding (which is even more ridiculous considering they spent less than $2K on the whole thing and how much their family and friends have pitched in and given them for free).

As others have pointed out, it's also likely illegal for them to do this without a liquor licence.