Although there doesn't seem to be any obvious evidence here that the US could be lagging behind. Per-person the US is still a bit of a productivity outlier to the upside. When they aren't legislatively restrained they tend to work hard and in an organised way.
Also if the US makes very expensive widgets, but can't make cars cheaply, it would still show up as high worker productivity. It's not really the same as engineering efficiency per (PPP) dollar.