Being in the wireless / mobile industry for 25+ Years, we can say that most major carrier stores (Verizon, AT&T, T-Mobile) will provide them for free (if you have a contract), however, minor carriers (Metro PCS, Cricket, H20, etc) usually charge for them. Many times calling customer service on the phone, you will get the official corporate policy, rather than risking a store trying to charge you in person.
Either way, though, they are not ALWAYS free.
Additionally, not all major carrier stores will provide them for free. Some stores (Verizon or not) will try and charge you. Depends on the store owner, management, etc. It is your responsibility as a customer to know what you are eligible to receive for free, what is not, and request those items. We always tell buyers that if they already have an account with the network that they should be able to request a new sim card for free in the event that someone contacts us about SIM cards.
The person or company selling the SIM cards is doing nothing wrong. For your information, for any non-corporate store or business, you have to pay for SIM cards. So the seller selling the sim cards is doing nothing wrong. They most likely purchased just like you did. Most people that do purchase sim cards do so because they either are, like you not aware that they can request one for free from certain networks if they already have a contract, or they live far away from a carrier store and do not want to go to a store to get one. So they order it.
If you lived 15 miles from a carrier store, for example and could not easily get to a store, you may consider paying for a sim card to save you time and travel costs. There is surely nothing unethical about selling something that customers will pay for as long as customers are not being mislead in anyway on the listing. It would be unethical if the seller had wording in the listing stating that you could not get them any other way than by purchasing from them, but we would assume the seller does not state that.
