It is common to see the bodies of those who have passed away being cremated by the bank of the Ganges River in Benares.
The fire smoke and fumes travel north into the city. Naturally, the odor is not good. Houses and buildings are constructed to face away from these fumes.
It may be that the writers of the Vedic literature, in this holy city, were talking about a local situation, not intended to be global.
Cremation is not practiced in other areas of the world. Many communities have zoning ordinances against such activities.
If we could be shown the specific chapter and verse references in the Vedas, to the southern entrance warning, that would help clarify this issue.