This is because the price of gold is very high when it is sold in a gold shop. When it is recycled, it is often repurchased with old materials no matter what brand you are and how high your technology is, so the price is relatively much cheaper.
As long as you bring your ID card or relevant documents, you can sell them anywhere.
Generally speaking, if you are an amateur, it is good to sell 250/g now. If you are lucky, you can be one or two taller. Hehe, the price of gold changes every day. Give a website a look for yourself. Having said that, you must give the best. Good luck.