Backup cameras are more helpful on recent cars (compared to decades ago) due to the generally worse rear visibility on recent cars.
Here is a recent example of worsening rear visibility on a redesign:
https://www.caranddriver.com/news/a28857236/2019-mazda-3-hatchback-visibility-rear-window/
https://jalopnik.com/the-2019-mazda-3-hatchs-rear-visibility-is-precisely-as-1830754940
Eventually, will we have to get used to driving cars with similar outward visibility to cargo vans with no windows behind the driver?