Chicago: Asian restaurants will bring you a pot of already-brewed, ready-to-drink hot tea. So will nicer Western restaurants that have an actual tea program. Coffee shops and mid-tier restaurants will typically give you a cup with the tea already brewing and it's up to you to remove the bag or sachet in a timely manner.
Everywhere else brings you a little tea-making kit consisting of hot water, teabag(s), and maybe lemon and honey. You have to ask if you want milk, except at oldschool diners.