A team of 10 software engineers is not necessarily better than a team of 5 engineers.
For some projects you need quality, not quantity.
With the cash reserves Apple has, you'd think if they were hungry/desperate enough to solve the Apple Maps problem, they would've paid top dollar and would've been able to attract quality people that could've made some huge strides within three years.
To this day, there are still areas on this planet where people live and work that look like a barren wasteland as far as Apple Maps is concerned. It's only if you switch to satellite view that you see that there are actually roads there. Apple Maps is one of the few modern mapping applications about which it can be said that an outdated satellite view is sometimes more accurate than the standard map view.