All of tlw's comments reflect my own experience working with young/inexperienced musicians and bands. In their head, they sound awesome. And garbage in, garbage out is the last thing they want to hear when they complain that you didn't make their drummer's $39 snare with heads that haven't been changed since 1971 sound as good as the snare Bonham played on Zeppelin III.
A quick and dirty (but otherwise clean and decent sounding) live recording was the proposed premise in the first post. You want the bass and kick a little less in your face because that's your perception of how your band is supposed to sound? No prob, email the mix engineer and revised copy will be delivered in a day or two.
But invite them in for the final mix session and next thing you know, you're spending 45 minutes with drum replacer because the kick and snare are ok but I'd like it better if the kick had more slap and if the snare was deeper, and oh can we pull the acoustic back a bit during the first verse but make it just a tad more up front during the chorus and then can you pan the rhythm guitar more toward center during the intro and solo, but not dead center, just closer to the center yada yada yada. IMO that's not what was originally proposed and its also why recording studios cost what they cost.
It'd be great to be able to offer that level of service to everyone for pennies on the dollar. But if you do, you'll either end up operating at a loss or you'll end up using mix engineers who are worth only what you can afford to pay them.
There's a sign that hangs in the lobby where I work. Good Fast Cheap, pick any two. When it comes to certain things these days, it really ought to read pick any one.