The main failure is not having something akin to a Google Scout, whereby iOS users could submit info about businesses and streets that lack data. Apple instead hires a ton of contractors in Austin (and now India) to manually trace roads and guess business hours based on anonymized GPS traces.
Apple lacks the scale of Google's army of unpaid Google Scouts (though they could easily fix this) and is wasting time on minutia rather than task their staff/contractors with sourcing & importing higher quality data regularly. One example would be importing county shapefiles, Apple could easily vault ahead of Google Maps if they diffed their map against each of the thousands of county maps in the USA, and they would be the only one regularly doing this (OSM does this occasionally, but not often).
They could also scrape business data from each state and use that to produce more accurate & detailed business listings than Google, among many other low hanging fruit.