NOAA keeps two sets of books, one that excludes bad data, and one made mostly of bad data. The latter is the one reported to the media.
It’s not necessarily intentional, an automated temperature station sited in a rural meadow doesn’t move, but the city limits do, and often urban effects, like buildings and parking lots, overtake those stations. Even a station still in a meadow but downwind of a growing city will be distorted.
The record of the valid stations for US temperature does show an increase over the last 40 years, but only about half that of the total station database. Why NOAA reports only the corrupted data is a mystery.