Why do Sunnis not demolish the grave of the Prophet, may God bless him and grant him peace, despite their saying that the graves of imams and ordinary graves must be demolished?

Demolishing graves that exceed the lawful limit is an authentic, explicit Sunnah (definition), and the view is that every raised grave must be leveled. The Prophet, peace and blessings be upon him, prayed: "O Allah, do not make my grave an idol," and Allah answered his prayer, so his grave was not raised high. Rather, it was raised about a handspan from the ground and humped, and surrounded by three high walls to prevent its worship. As for the polytheists affiliated with this Ummah, they worshiped the graves of their imams and sought help from them, building magnificent structures over them and performing acts there similar to those performed by idol worshipers. These are the graves that deserve to be demolished.