I hope you do realize that is only part of the frame. Notice the flat pieces at the end with cut out slats? That is for you to bolt a head/foot board to. In fact that "standard" frame typically comes with that end piece on both ends. (IE: Head board & Foot board)
This is done so the buyer can decide what head/foot board style they wish to add on. Its basically the frame for the "ill upgrade the frame later" buyer.
Further, when you buy a bed, you typically are buying the mattress, the foundation (IE box springs). Typically in the US they are sold in bundles, like Pay X amount for the mattress, get the foundation for a dollar, or something of the like. The frame is usually not included, or if it is, it is this manner of frame that allows you to build on to it for making the choice of not purchasing a proper frame outright. Usually this is the type of frame that is a "freebie" throw in, because the frame typically only costs about 60$ MSRP, whereas a normal frame would cost every bit as much as the mattress & foundation, if not more. So if you bought your first mattress & foundation combo, be happy they threw in anything at all because at least in the US, the frame is a separated purchase from the mattress and foundation.
In fact it is actually sort of rare to see a bed plus a frame sold as a bundle because it is sort of illogical to do so, as retailers do not want to bundle a frame to a mattress whereas potential customers might not like the frame that goes with the specific bed, or vice versa and would end up with people trying to mix and match based on their existing furniture. Or, what is equally as common, selling the bed frame as a part of a bedroom suit, that can accept any of the standard bed sizes. Twin, Full, Queen, King, ect.
To give a rough breakdown, a full size mattress typically starts at about 200$, Foundation, about 100$. A frame can start as I said about 60$. However things like headboard/foot board, rails, drawers, ect are all considered accessories. A full size headboard typically starts at roughly 100-150$. Full frame sets run around 300$ and up. So if you shelled out around 300$, dont expect more than a mattress and box spring. A bed + a proper frame for it, that isnt the "standard" "Ill upgrade it in the future" type, should start at about roughly 600$ and upward.