I would also be reluctant to mow everyone's lot - you're sending conflicting signals about pride of ownership and tenant responsibility. I would increase the penalty for not mowing to help cover the extra administrative costs.
I also give a lot of autonomy to my managers on these subjects to limit my time involvement. My on site manager has access to violation forms, and the ability in our property management software to add penalties to any lot. They're trained if this happens to take photos documenting the item, issue a violation notice, and then add a fee onto the resident's account. There's minimal headache on my end.