In London the biggest private hire cab firm that isn't Uber is Addison Lee. They sometimes send out a notification along the lines of "It's the weekend, enjoy it with us: £5 off your next 4 trips". Perfect. In the past I've changed my plans around that sort of advertising.

In an email, I'd miss it. It's timely, context aware advertising from a brand I'm happy to use and hear from, particularly in that moment.

The key here is that I can opt out of them, not that they appear everywhere no matter what: I can tell companies if I want to hear more from them in this manner.

I subscribe to a "price alert" for a product in my sellers app. The price gets triggered, and because there's a lot of demand for this item, I have to be fast.

This, for me, would justify the "push notification".

But, would this also be considered an "ad"? From the definition of the word "advertisement"[1], which says it's "a notice, picture or film telling people about a product, job or service", it would qualify as an ad.

[1]: https://www.oxfordlearnersdictionaries.com/definition/englis...