McDonald’s is somewhat premium in many countries, the idea that it's poor people food is US-only but isn't even true here. Poor people work at McDonald’s, they don't eat at it.
Also, poor people absolutely eat there. All those poor people working there get free food and employee discounts, others use the app, or they eat there once in a while as an alternative to more expensive restaurants.
Maybe I get that impression a little less in the UK, but that's only because their food isn't bad enough for British people to like it when they could be eating smack barm pey wet.
Also, by somewhat premium I mean in the same category as Starbucks, not a sit down restaurant.