Behavioral data often reveal differences that don't show up on surveys, where answers are free and often aspirational. Data show, for example, that men donate more than women while people who support charities more also have more conservative political stances. The rational is they choose the organizations they want to help, the ones doing work they like. Yet if you get a coffee paid for by the person in front of you at Starbucks, it is likely someone on the left. Charity and generosity are often distinct. 

A new survey isn't actual behavior but it does lend to the belief that left wing people feel like they are more altruistic. 

The ~68,000 responses from 68 countries were organized by the International Collaboration on the Social and Moral Psychology of COVID-19 (ICSMP COVID-19), which examined psychological factors underlying the attitudes and behavioral intentions related to COVID-19. It was taken April and May of 2020, when enthusiasm for government solutions was still high.

Participants were asked to self-identify their political orientation on a scale from 0 (very left-leaning) to 10 (very right-leaning). To measure generosity, researchers used a donation choice - no real money - for a national charity and an international one. The task consisted in answering what percentage of a sum of money people kept for themselves, and how much they gave to a national or international charity working to protect people from COVID-19.

Using those three options, they speculated about generosity in general and their belief in localism or internationalism. They found that left-wing people preferred large, centralized charities and right-wing people donated more at home, while with virtual money left-wing people donated the most. Since this was early in the pandemic and COVID-19 had not been turned into a political issue, the authors were able to control for right-wing people perhaps distrusting COVID-19 charities less or not believing it to be a threat.

Instead, the difference was more about how capitalist or socialist the countries where people responded were. Countries that prize initiative were more likely to help those at home while those in countries with greater control by government believed that international was better use of the money.

The world has become increasingly globalized, and that is raising the standards of living for all, which may mean a benefit for multi-national charities if the countries where standards rise have greater government involvement in the lives of citizens.