It found rush hour by itself

Look at the first column of the hour factor matrix. The strongest pattern peaks at hour 18 — and that is also the busiest hour in the raw counts.

The decomposition discovered evening rush hour by itself. Nobody told it about time, traffic or commuting. It found the dominant pattern along that axis, because that is what a decomposition does.

This is the result worth carrying out of the section. The 4.7× compression is the cost saving; this is the reason to decompose at all.