Peasants' lives are cheap; it's already good enough to snatch back the life. How could they afford ginseng whiskers? As long as he didn't die, he just needed to take some cheaper medicine, go home, and recover slowly. After all, Eldest Brother's life is tough, so he should be able to pull through.
By eliminating the ginseng, the cost of the medicine could at least be halved. This way, the Li Family's compensation should be enough, and their own and the head of the family's coffin savings might even remain intact.
As for the subsequent medical expenses, what were Lady Lin and Eldest Brother's two sons for? Surely, they wouldn't be unable to recover the money for their own husband's and father's medicinal costs, would they?
Calculating this way, the outcome was much better than the expected complete financial ruin. With her own interests in mind, Old Granny Zhang settled the bill with Doctor Ma extra efficiently.