There was also some discussion in the comments about OP’s mom possibly having ADHD, which would explain her chronic tardiness. However, one person with the username u/RickyNixon gave their perspective.
“Its a choice. Like, she could be on time if it was important to her. Chronically late people simply do not respect others enough to be punctual.
I have severe ADHD. When I’m supposed to arrive at a certain time, I set alarms. ‘Start getting ready’ alarms. ‘In case you’re distracted, get back to being ready’ alarms. ’15mins until you have to start/leave/whatever’ alarms. Sometimes 2 hours of alarms to ensure I stay on track and arrive early.
I respect others. I respect their time. So I don’t let them wait on me. I have a disability that is associated with lateness and I work hard and inconvenience myself to ensure my loved ones know I care enough to be where they need me on time.”
Source: https://www.buzzfeed.com/jenniferadams2/aita-son-mother-wedding-time