pretty extreme opinions, but worth of a response.

I can only speak of LH, haven't flown anything but LH & EK to India in the past years.

LH always has 2 indian FAs on their flights to India, who originate in India and have a different duty schedule and contract (which is better than the german contract BTW). These two have to help in the announcements and most importantly translate for the other FAs. Not only language, but social behaviour too.

LH FAs are very sensitised during their training to know how to behave towards Asians, be it Japanese, Indian, Middle Eastern etc. The veggie option has been addressed via a veggie menu choice, but still people preorder veggie meals and get separate service (the P1 goes thru the cabin to make sure the persons with the special meals are in the seats shown in the manifest etc) Other pax notice and suddenly decide to have a special meal too. If the veggie choice runs out the situation quickly escalates and the indian FA is called to mediate.
Last week I witnessed a discussion in the galley where an elderly gentleman claimed he was diabetic and was upset that LH didn't load atleast one diabetic meal on each flight. The argument that your TA has to preorder such meals didn't count. The FAs still scrambled and gave him fruits and other goodies from the crew meal.

OTOH I have witnessed pax just not caring: the toilets are often quickly in a fairly disgusting state. The FAs on the watch in between meals have to inspect the lavs and shut down any lavs that are inop or completely dirty. The frustation does add up when you are working and 3-4 uch incidents happen on one flight. So I can understand why they snap at someone.