Dream control and lucidity are not synonymous. You can have a non-lucid dream with near complete control or a lucid dream with very little control. In a lucid dream however, dream control is a skill. Some people have great control right from the start. Others need to practice and learn techniques to help them accomplish their dream goals. If you wanted to summon a person then you could. Dream control, in general, is only as difficult as you think it is.