system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do fast food and casual dining places need to nickle and dime us on some things but not others?

Taco places charge for sour cream and guacamole but you can take as much hot sauce as you please. Burger joints make you pay for dipping sauces but freely dispense ketchup, mustard, and even mayonnaise. Wing places will add a price (sometimes without telling you) for ranch and bleu cheese while again giving away other free condiments. Is this to actually justify different costs or is it a money grab to squeeze every penny possible out of us?
gpt
There are things that are considered traditionally part of the dish and things that are considered additional.  A burger isn't a burger without the dressing and in order to compete you have to supply those things for free just like every other burger joint.  Dipping sauces are part of a different menu item so to get it you need to pay for the difference in cost.

Guacamole and sour cream are significantly more expensive than salsa and they do not keep for anywhere near as long.  Taco Bell can make salsa by the truckload and distribute it to their stores as needed.  It really doesn't cost them much to produce and keeps for a long long time so they can buy ingredients when they are cheap, produce a ton and then wait out winter months or bad seasons.  Guacamole takes actual manual prep and spoils very quickly as does sour cream.  The price for avocado and milk also can change drastically in short periods of time so not including them in the base price of the item makes it easier to alter menus and keep things standard across the chain. Same thing applies to the wing sauces you mentioned.