So what is scope creep?
You know when you order a sandwich at a restaurant, maybe a salami sandwich, the waitress brings it to you. You look at it, say you know what, I'd really like some mustard with this, could you please bring me some. Waitress comes back with mustard. Oh miss, you know what, I'd really like this on a challah roll, could you do that? Sure, the customer is always right, be right back. She returns with your salami sandwich with mustard on a challah roll. Oh miss, I'd really like a pickle, could you please bring me one. Sure I'll be right back. Miss, I've decided I'd really like a coffee instead of water and lemon, could you please bring me one. Thanks. Oh miss, I'd really like an extra cream for my coffee, could you be a darling? Oh miss, can I have some extra nakpkins? Oh miss, can you please split the checks? But sir, you're eating alone. Doesn't matter, customer is always right.
And there you have scope creep. The customer is not always right. There are limits to what you get when you buy something. There's some leeway, but if you take advantage of it, you will have to shell out extra money. It's not an all you can eat buffet of unlimited changes. There's time and effort involved, which translates to $.