I can see how the rythm of the class can be broken by someone being late. Hearing the door opening and closing and seeing someone pausing at the edge of the mat with an excuse ready on their lips is just kind of sad. Most of the time, the excuses are something like "I tried o get here on time, but I forgot." Sheesh. Most of the time it is people who have been taking at this same time for several years.
I don't know what dojo you train in, but I guess I just got lucky.
No one in this dojo (including the instructors) is ever judgmental or negative toward anyone, including those that are late.
Have a nice day