Yep, simple oversaturation of the market. Dollar General is well-known to pop-up everywhere there isn’t a Walmart or sizeable grocery store. I’m sure Dollar Tree isn’t any different. Dollar Tree owns Family Dollar, and I am surprised the Family Dollars didn’t get shut down or rebranded already.
We used to have a Family Dollar store, and it was rebranded as a Dollar Tree. There’s also a Dollar General about a mile away from the Dollar Tree. I rarely shop in either. I try to stay away from stuff made in China, though sometimes they have what I’m looking for when nowhere else does.