Median income in, for example, Detroit was $58,411 in 2017. Post-taxes that would be $45,484. $3300 is about 7.3% of that so, yeah, that's a pretty hefty bite.
Even assuming the median earner is paying the average for eating out (e.g. is a blue collar family of 4 in the Midwest spending the same proportional to income eating out as a childless professional couple on the coast? I'd wadger no.), you still need to compare that against the cost of groceries. So, it's more of an additional 3%-5% in reality, not a whole 7%.