There was a theory that the virus doesn’t fare well in hot climates and that seems to be playing out.
A good example of this is Vietnam. Nearly all their cases have been in Hanoi which has quite temperate weather in the winter versus Ho Chi Minh City which is tropical all year around.
It’s not the only factor, but it does appear to have an impact.
Also consider that in India, there is not only a massive population, but access to tests per capita is probably quite low. Furthermore, the background noise of other infectious diseases is higher there, so many of these cases may go unnoticed or just attributed to common ailments. Death by infectious disease, while tragic, is somewhat more normalized there, and it might be hard to convince a lot of people not to go about their daily lives.
https://www.statista.com/statistics/1099662/china-wuhan-coro...
India: 1.3B population and right next to China. Greece 10M population and no close land links to China.
These numbers don't pass the common sense test.
In terms of Greece, it's more like Japan or China than a tropical country.