I do think that the whole dynamic has changed for how people prioritise their time and energy and gardening is one of those pastimes that takes effort and to the untrained eye may not look any different after having spent many hours, mowing, weeding, pruning and sweeping every week.
I live on an old, well-established estate and I would say 99% of gardens look very well kept. However, I back onto a council estate and the back gardens of the 2 houses directly behind me are very unkempt.
The grass has been left to grow about knee high in places and conifer trees left to grow upwards and outwards, basically reducing the quite large gardens to a small patio area by each of the back doors to the properties.
I know nothing about the people who live on these houses, so could not say if they do not have the capability of tending their gardens, but I suspect that as they are council properties, there is less inclination to do anything to keep the outside presentable.
My late mother, passed last year at 84 years old and she kept both the front and back garden of her home immaculate. She did need help to mow the lawn and cut the conifers back but other than that, she did it all - painting, sweeping, weeding, planting, watering and trimming back. Everyone in her street marvelled at what she used to do, especially new residents moving into their new homes.