Unfortunately it's usually only illegal when a monopoly or other dominant company does it. SV seems to have worked around this by funding "startups" so much that they have the capital to engage in dumping before becoming dominant in an industry.
at least in the US doordash already reached more than 50%. i believe if it can be argued that it was only able to achieve this through predatory pricing then at this point it should be possible to stop it from continuing that pricing strategy.
