It's unclear exactly which lights you're referring to (none of the example pictures you linked to are red), but the FAA AC on obstruction lighting says that only structures over 200ft are required to be lighted:
Any temporary or permanent structure, including all appurtenances,
that exceeds an overall height of 200 feet (61m) above ground level
(AGL) or exceeds any obstruction standard contained in 14 CFR part
77, should normally be marked and/or lighted.
However, there are exceptions:
The FAA may also recommend marking and/or lighting a structure that
does not exceed 200 (61m) feet AGL or 14 CFR part 77 standards
because of its particular location.
The same document describes the use of red lights:
Aviation Red Obstruction Lights. Use flashing beacons and/or steady
burning lights during nighttime
The rest of the document suggests that red lights are for night use and white for day use. The FAA also has a dedicated portal for obstruction evaluation and reporting if you're involved in building or managing potential obstacles.