The fireman's axe has a yellow handle and silver blade, and there's the 2-colour modern rifle, so Playmobil have the means to produce more realistic wooden-handled tools and weapons, they just haven't set up for it yet for other items.
At present a lot of tools are produced in groups on sprues of one colour, but I suspect that in the next few years we'll see more realistic tools appearing, which will look especially good for long wooden handled tools and weapons like shovels, spears, halberds and 2-handed axes, as long as the cost isn't considered prohibitive.