Not really, there are often other options. Different lots nearby using different systems, for instance. Or the option of simply not paying and risking getting towed / a ticket.

A parking lot clip could use the time-based notification to warn you that your meter is almost up and give you the option to re-up. Without having to walk back to the lot to do it. I imagine this would be especially useful in a tourist-heavy area since somebody who isn't sticking around won't want to download a whole app for the purpose.