On non-touch devices, the reach for placing a block is much more than those of touch devices. When you try to place a block whilst jumping on touch devices, the block doesn't place. The reach to is less on touch devices. For eg, whenever I try to place a block at least 3 blocks away from me (above void/air), the block doesn't end up placing. I know on touch you cannot code a specific button which can be pressed down like right mouse button on mouse, but I don't think the reach works as intended.