Counterintuitive data: strikes edition

Check out this graph from the Economist:

I find these data pretty surprising:
* Three countries - Germany, Netherlands and Sweden - with strong labour protections lose fewer days to strikes than the US or UK
* Germany and Japan seem to lose something like an order of magnitude fewer days to strikes than the US (!)
* France is just a touch above the OECD average, losing a little bit more than the US, but fewer days than either Australia or Ireland

Is it just me or are these numbers just a little counter-intuitive? I would have expected countries with strong labour protections to lose more days to strikes, and for France in particular to be an outlier. I would have expected the US, and to a lesser extent the UK, Australia and Ireland, all thought of as places where it's easy to hire and fire workers, to lose far fewer days to strikes.

But that's not what we see in the graph. Are these numbers right? Or is this one of these things like unemployment where off-the-shelf numbers need careful interpretation?

(The right would expect easy hiring and firing, weaker worker protections etc. to mean less unproductive striking, with the market taking care of who should get how much etc. The left would expect more strikes in countries with the "worker friendly" policies they like, but they'd view those strikes positively as a mechanism by which workers collectively express preferences. Surely both camps would find these data a little surprising?)