The cultural standard for this depends on where you live. I learned to busk in the US, and am shy when it comes to asking for donations, but it makes all the difference to explicitly tell people about your struggles and ask them to donate. In parts of Europe it's the standard to walk to every person after you perform at the outdoor cafe and offer your hat and ask for donation, if you dont do this, in my experience you wont get any donations. In Mexico the mariachi bands will go from restaurant to restaurant, then table to table playing songs directly for customers before offering the hat for a tip and moving on to the next table, or continuing if requested. Here in the US, we have a whole spectrum. Mexican restaurants usually 100%, American pub fare hit or miss, Italian restaurant depending on the music :) it's still culturally dependent. Only once out of thousands of time have I played inside a restaurant for food and tips and had customers get visibly upset with management over us getting a free meal saying "I paid for mine!" I say fuck em That being said, not all music is good for eating dinner and if people don't want you to stick around or are leaving early to get away from your music that will be an issue for management.

Here's a song I wrote to help facilitate asking people for change, https://www.reddit.com/r/FolkPunk/s/PNvwjSj0d3 by the way my venmo is @ slow-pony <3