It seems the airline with the union has strikes more often than the airline that doesn't. Is that a true relection of the situation?
That is a true but wildly incomplete version of the situation.
Here is an extract from the
wikipedia article on striking...
"
Occasionally, workers decide to strike without the sanction of a labor union, either because the union refuses to endorse such a tactic, or because the workers concerned are not unionized. Such strikes are often described as unofficial. Strikes without formal union authorization are also known as wildcat strikes.
In many countries, wildcat strikes do not enjoy the same legal protections as recognized union strikes, and may result in penalties for the union members who participate or their union. The same often applies in the case of strikes conducted without an official ballot of the union membership, as is required in some countries such as the United Kingdom."
So you see why companies without unions have less strikes? A non-union strike is a very rare thing and may put people at more risk. Not having a union also makes industrial relations between staff and company that much more difficult to conduct and is usually at a disadvantage to the staff. In many industries, aviation included, unions are a necessary part of everyday life that actually don't cause strikes at all but try their best to avoid them.