Names and logos = trademarks In any case, the issue of using a sports logo isn't a copyright issue (Don't worry about the confusion -- apparently even the editors of the Daily Beast can get it wrong -- see above.) The unauthorized use of a team's name or logo on a t-shirt violates the team's trademark rights (as does the use of peripheral marks such as "March Madness").
How do they get away with it? People "get away" with trademark infringement for two reasons: (1) the trademark owner isn't aware of the infringement, or (2) the owner is aware of the infringement but doesn't consider it worth pursuing financially (or from a PR point of view). If you wish to obey the law, then you shouldn't use the logo or name. If you want to use a sports logo anyway, then, (as you can probably guess), you're more likely to run into problems, the more well-known and well-publicized your band becomes.