I disagree. Team leads are chosen for a reason and when they clearly ask for a task, it needs to be done without the wasted effort of having to convince them.

> If it's so easy, why didn't the lead just do it himself instead of making a problem out of it?

It's called delegation. If there are 15 easy tasks, a team lead can delegate them out using his or her judgement and have them completed quicker than doing it themselves. If each of those easy tasks has to go through a "convincing phase" it's no longer worth it.