It is true that many Indian languages do not have a time specific greeting. This is true of Hindi, Gujarati and even Punjabi. If you wanted to greet someone, there are standard terms used to greet people which can be used any time of the day.

Or else people use the English terms.

'Namaste' is a greeting term used which is widely used in Hindi. 'Namaskar' is more Sanskritised and is less prevalent. 'Namaskar' is used more in written language and not in spoken Hindi. 'Namaste' is just a way of asking the well being of the other person.

In Gujarati, for instance, if you wanted to greet someone, you would say 'kem chho?' which means 'How do you do?'. In Gujarati, you would not even use the customary 'Namaste' which is used in Hindi.

This is an issue that deals with cultural difference.

Similarly, though the words for 'Good evening' exist in Pilipino [Filipino/Tagalog] language but in actual practise, the term 'kamusta ka' meaning 'how are you' is used.

I hope this helps.
Regards
Roomy Naqvy.