Computers disallow passengers to check in at 30 minutes or less to scheduled departure of a flight. You showed up late and were not allowed to break the rules. In what way were you disrespected??
D)
Check-In Time Limits - UA has the right to cancel reservations (whether or not confirmed), deny boarding and/or refuse the acceptance of checked baggage of any Passenger who fails to present himself/herself within the applicable check-in time limit for Passengers and/or Baggage.
1)
Domestic flights, except those departing Guam:
a)
For Passengers who do not need to check baggage, Passenger must complete the purchase of the ticket(s), check-in and obtain a boarding pass at least 30 minutes prior to scheduled departure.
The dreaded Contract of Carriage
Page 10, para D