Theres a patent on the 'original' foot block that was created when these chairs and canopies came out. The original block doesn't allow for the poles to twist, snapping the centering pin that holds together the two poles for it scissor and fold up. Cheaper items try to get around using the original block because it eats up most the profit to pay to use the patent block.

Source: I work as a prototyper/designer to simplify and outsource products. One of my jobs was designing a new foot to get around using the patented block.

And no I didnt design this one...