The famed B’nei Yisas’char, Rav Tzvi Elimelech of Dinov zt”l, used to say: “Why don’t we make a blessing before we give tz’dakah, the way we make blessings on everything else? Because, had we been commanded to make such a brachah, the poor person could have very well starved to death by the time we finished making our blessing! If the baal ha’bayis is a chasid, he would first have to go to the mikvah, then he would have to recite a lengthy l’sheim yichud. If he was a Litvak, he would undoubtedly learn up the sugya in order to do the mitzvah mehadrin min ha’mehadrin! By the time he got through all the preliminaries, the poor fellow would most probably have dropped dead!”