Some complained about the wastage of fruits near their estate. Others questioned the logic of prohibiting plucking of fruits. Many complained about the senseless prohibition.
To me, there is always a reason for prohibiting things in Singapore, e.g. the famous chewing gum ban, the no smoking within certain distance, no cycling at designated places, no littering, no loitering, no fishing with live bait, no playing football in void deck, no skateboarding in walkway, no open burning (except in allocated drums), no trespassing, no cluttering of personal furniture/belongings outside HDB flat, among others. Just because we might not get the meaning of the ban/prohibition at first, that shouldn't stop us from seeking answers (or deduce by reasoning).
As for the topic of this entry, why are we prohibited from plucking fruits from trees surrounding HDB estate? I can come up with several reasons.
First, if there is no ban, there might be mass-harvesting of these fruits by certain party (due to "kiasu" [afraid to lose out] culture). They could later sell these fruits for a profit (without any cost to them), while killing the livelihood of legitimate fruit sellers.
Second, the fruits hanging on the trees are not completely gone to waste. These fruits are food to the faunas in Singapore, such as birds (e.g. Alexandrine Parakeet [Psittacula eupatria] eating an unripe rambutan fruit [Nephelium lappaceum]) witnessed by me today!), squirrels (if they are there in your estate), insects, insect- and fruit-eating bats, and many more. Furthermore, once the fruits start falling and rot, they are compost to the surrounding vegetation.
Third, if it is illegal to pluck fruits from trees, there is no liability on the part of HDB if anyone should fall or injure themselves.
Fourth, to prevent illegal fruit sellers from harvesting these fruits (not belonging to him/her) and selling them (just to emphasize this point again).
Just a thought.