I don't understand....

I don't really understand the contemporary union setup.

I understand that unions were invented after the industrial revolution in order to protect workers' rights. I understand that at that time workplaces were dangerous and even more exploitative than they are now, and so workers stopped work en masse in order to bargain for better situations.

But when did strikes become "legal" or "illegal"? Isn't it in the nature of a strike to be a workers' action taken against the powers that be?

As any Torontonian readers of this blog know, the TTC went on strike this week without much warning. I don't really know much about the issues at stake, and I'm not that interested.

What I want to know is: what's the point of going on strike at all if people can just order you back to work? Isn't the whole point that they can't fire you all at once? Strikes are supposed to give workers the upper hand; that's why they were invented. But it seems that nowadays that isn't the case at all. So what's the point?