earth - 22nd is shortest day in some places, but the 21st is shortest in other places. Can this be true?

EDIT: Ignore below, see comments for correction.

@DavidHammen, I ran your script with start and stop year both set to 2096, and got this:

('December solstice in', 2096, 'is at', 2096/12/20 20:45:17, 'UTC')

Shortest day of the year, by longitude:
Date  Longitude
('12/19', -180)
('12/19', -170)
('12/19', -160)
('12/19', -150)
('12/19', -140)
('12/19', -130)
('12/19', -120)
('12/19', -110)
('12/19', -100)
('12/19', -90)
('12/19', -80)
('12/19', -70)
('12/19', -60)
('12/19', -50)
('12/19', -40)
('12/19', -30)
('12/19', -20)
('12/19', -10)
('12/20', 0)
('12/20', 10)
('12/20', 20)
('12/20', 30)
('12/20', 40)
('12/20', 50)
('12/21', 60)
('12/21', 70)
('12/21', 80)
('12/21', 90)
('12/21', 100)
('12/21', 110)
('12/21', 120)
('12/21', 130)
('12/21', 140)
('12/21', 150)
('12/21', 160)
('12/21', 170)
('12/20', 180)
()

I take it you're getting different results?