but to strike fear into the heart of the capitalist, you must provide a credible threat that you can keep on striking indefinitely, and that requires a lot of work and a lot of organization

Or, threathen to make them actively lose money. For example, where I live it is legal for bus drivers to strike.

But they can’t strike by continuing their route and not charging for the ride. They explicitly made that illegal, making a general public transport strike not only less effective but it also turns the public against them because they are inconvenienced. All intended, ofcourse. Deny the workers an effective method of striking while still being able to say that they are “allowed” to strike.