I spent time with my niece yesterday but I’d be able to stop by work at some point if I wanted to or needed to. It would be my choice. As someone else mentioned people in service industry often change their schedule to accommodate clients. Like hairdressers would work on their days off if clients needed that day or maybe his plans to see so and so were at a different time on Sunday etc

We don’t know your friend so it might as well be that she’s inconsiderate, but just judging by this one event it’s impossible to tell. Is she considerate with you? You can’t really judge her arrangements/relationships with others as no one knows those details