But I've noticed that even when they're speaking English to people of OTHER nationalities, they use "crore" (10 million) and "lakh" (100 thousand) and expect everyone to know what these are!
Why don't the Indians understand that "crore" and "lakh" are words in their own languages, not in English? Even if they are used in English in India, they're called "dialectal terms" at best.
In Chinese, we use "wàn" to refer to 10,000 and "yì" to refer to 100 million. But we'd NEVER use these terms in English. In English, they're "ten thousand" and "one hundred million". There's a distinction between languages.
Do Indians honestly believe that Britons and Americans use "crore" and "lakh" too? Because South Asians are the only people in the world who do :-)
(Just as we East Asians are the only people who use "wàn" and "yì" and variants, e.g. "man" and "oku" in Japanese.)
更新1:
Haha, no, it doesn't matter to me at all, since I understand these words :) But my father was very confused once by an e-mail he got from an Indian business customer that was full of crores and lakhs, so he had to ask me to translate it for him :p