Meat wave tactics don’t need voluntary compliance. If you don’t go they shoot you, if you try to signal the other side with some gestures they’ll snipe your ass.
Russians march them towards Ukranian positions in Russian uniforms. When Ukranians open fire they’ll know their positions and call artillery, or Ukranians call artillery and soon need to change their artillery positions, because there is a chance Russian have triangulated their positions. After that the main force attacks.