Other Reddit users shared their thoughts on the situation, saying people underestimate retirees because they think they're too old to care. Also, others added that the old woman didn't do enough to punish them as she should've left her car behind them for at least a week.
Some people confirmed that it's an old age thing where people care less who they offend because they have little or nothing to lose.
On compliance issues, Reddit users suggested that the apartment complex create a contract with a local tow company and punish people like the couple for bullying others. Someone noted that the $150 the Granny requested to move her min-cooper was a steal compared to towing fees.
Another person turned to technology, saying they solved the problem in their apartment complex by locking the garage electronically and giving only the people entitled to access to the space.
The last two suggestions are the most viable options, although it's nice that the Granny got her vengeance and the couple suffered public embarrassment. Never purposely take advantage of retirees - apart from bad karma, they often pack a mean punch, and you'll never expect what's coming.