Indian e-visas have been reinstated for citizens of 156 countries, but notably not the UK or Canada. Does anyone know the official reasoning for this? I presume it's an attempt to get those countries to negotiate better free trade deals, though presumably the travel troubles are more of an issue for India than it is those countries.

Applying for regular visas or OCIs takes months longer than earlier days, so it's not as valid an alternative. Lots of people missed holidays and trips back home to their native country as a result this summer.