I think it is also more than that. In car-centric places like Brazil or the US, older people essentially need to drive or be driven around to have a social life. In pedestrian friendly cities like many in Europe, it is very common to see older people walking to meet their friends/relatives. I saw it all the time in Switzerland. Even those with severely limited mobility would prefer to actively walk or take the tram/bus somewhere (no matter how much time it took) than stay at home.
Can agree with this (to a certain extent). Spending time in both America and Ireland, there's a definite difference in the extent to which "I can only get there by car versus public transit/other types of transport" is incorporated into the culture. By far, more urban/suburban/rural density with appropriate public transportation support leads to more freedom to walk, bike, etc. Geographically, however, there are clear reasons why places like the US and Brazil have a strong incentive to rely on cars over anything else. Distance between cities and towns, poor public transport (esp. outside of urban areas in the US), etc. cause this to be an issue.