Question:According to Rava, the tailor in the Mishna is going out with the needle in his hand? If so, then why just a tailor? Anybody should not be allowed to carry anything. Is it because Mishna speaks of the usual circumstance?
You are correct -- the Mishnah is expressing this law in terms of the usual circumstance. See SHULCHAN ARUCH OC 252:6 and MISHNAH BERURAH 252:51 who actually rule to this effect (that a person may not go out with any object near sunset on Erev Shabbos), although in 252:52 he writes that nowadays when there may not be a Reshus ha'Rabim d'Oraisa, it is permitted to carry an object on Erev Shabbos near sunset (because otherwise it would be a Gezeirah l'Gezeirah). See there for the other details of this Halachah.