Weak Pingers
"Why then are pingers so weak?"
Before about 1980, airliners had no pingers. Can you imagine how many pingers have been built that were never used at all? Many thousands. There have been only a handful of accidents in the last 30 years where a pinger speeded recovery of the recorders, let alone being crucial to success.
The return on investment in pingers has to be pretty poor.
GB