The virtue signalling about this is so weird. You do all realise that zero hour workers make literally no money if they don't work, right? I did zero hour work for years, and an unwanted day off could easily leave me with no money for food or other essentials. I still remember being annoyed about an extra bank holiday because it meant losing an entire day's pay I couldn't afford to lose.
If a delivery rider is choosing to work today, then let them. Give them a big tip if you feel bad about it, but depriving someone of income they need because of a virtue signal is bloody weird.