When you strike, the goal is to inconvenience or otherwise impact the users of the service. That’s how you hurt the service provider.

When the bus drivers strike, who does it hurt more? The public transit office? Or riders?

When grocery store employees strike, that has direct impact on shoppers.

When the writers guild strikes, the most affected are filmnand television viewers.

The whole goal is to affect change by altering the behaviour of users. Otherwise, you just get scabs.