why do you think the Sherman Antitrust Act and other attempts at regulating monopolies and trusts were not effective?

For more than a decade after its passage, the Sherman Act was invoked only rarely against industrial monopolies, and then not successfully, chiefly because of narrow judicial interpretations of what constitutes trade or commerce among states. When it was first passed, the Sherman Antitrust Act was largely ineffective at stopping industrial monopolies. Courts at the time tended to hold a very narrow view of what constituted “trade or commerce among states,” and most companies were not held liable under the act. For more than a decade after its passage, the Sherman Antitrust Act was invoked only rarely against industrial monopolies, and then not successfully. Ironically, its only effective use for a number of years was against labor unions, which were held by the courts to be illegal combinations.