$18/hour is just barely a living wage in NYC. Actual living wage for an adult with 0 children in NYC is about $25.50/hour:

https://livingwage.mit.edu/counties/36061

On top of that you have the challenges specific to these jobs. If you’re on bike, that’s hard work and limits the hours you can do without risking injury. If you’re driving (which is maybe practical in outer boroughs) you’re shouldering all the costs of the vehicle working for a delivery app. Either way that’s way too little after taxes per month, even at $18/hr.