Before anyone suggests that a tip is required in these instances, I'll preemptively remind you that Grubhub already takes AT LEAST 30% from the provider. A default tip by the consumer of 20% would suggest that their delivery service was worth MORE than the provider's food.
Here is a restaurant showing GrubHub fees (not including tips) constituting more than 60% of of the take.
https://www.eater.com/2020/5/1/21243966/giuseppe-badalamenti...
If drivers need more wages they should get them from Grubhub's already overly generous cut of the pie.
If someone appreciates a prompt delivery or other aspect of the provided service then by all means, provide a tip but that should be the carrot, not the status quo. If it is "expected" then Grubhub should just lump it onto their already outrageous fee structure.
Lack of proper pay for service workers in America that has resulted in our out of control tipping culture has always made me a little sick.