Google Wallet has gone through numerous changes in the last few years. Some were a response to Apple Pay but many were done well before Apple Pay. I don't think Google needed Apple Pay to exist before it took payments seriously. It just needed better support from phone manufacturers, carriers and payment processors. And Apple Pay has helped Google just by pushing all of those areas.
It went through many changes, yes. But the problem wasn't so much that they didn't take it seriously. As an online payment gateway it's used in quite a number of things, not just Google properties. Then there's their cash sending via gmail, etc.
The problem with Google Wallet on the handset, from the very beginning, was that the carriers decided to do their own thing. AT&T, Verizon, Sprint, etc... who remembers the name before Softcard? Yes, ISIS. There was another name before that too I think. They blocked Wallet from being preloaded on their phones. Furthermore they blocked bits of the hardware necessary to make it function properly. As Google adjusted, they adjusted.
ISIS/Softcard wasn't the only problem. They had huge problems getting retailers to update their card swipe machines to support contactless stuff. And then ISIS interfered and some of them started blocking Google. In the end, Google worked around a bunch of this stuff, but at that point the momentum was gone.
By the time Apple Pay came around, much of the fighting was already done. I think the folding of Softcard is evidence of that at least. And I remember thinking to myself "now that Google made the push for more contactless stuff at retail locations, maybe Apple and it's iSheep will bring the push that takes it over the edge."
I still think the jury is out on whether it'll succeed long term, but I'd hope people would think twice of accusing anyone of copying on this, especially when the other parties did a fair amount of the historical heavy lifting.