First, let me disclose I'm generally anti-union. But that said, I hate misguidance and half-truths in our media even more than unions, and in this case I believe they've been cited unfairly. I don't know if the news media is just too stupid to actually understand compound growth, or if this is intentional misguidance.
The demand was for a 40% increase over term of contract, which is a 4-year term, as I understand it. That would be equivalent to 8.8% per year, to reach 40% after four consecutive years.
In reality, they demanded 10% in the first year, as they feel they've fallen behind. In this case, the remaining 3 years would need to average 8.4%.
Those are still some large raises, but for the news media to pretend they're asking for a 40% raise on day one is misleading the public.