The worst single roll on the Injury table can result in 10 points of stat loss... that's Cr50,000 worth of medical bills, and there is always a chance that the employer will not pay. This level of pain may well result in an injury crisis, slugging you 1d6 x Cr10,000 of extra costs.
Also, while Merchants are one of the safer careers (unless this has changed with Merchant Prince), you might have a character who has done time in another, more dangerous career before or after who has landed one of the "roll twice on the injury table" results and exceeded this. A TRULY unlucky character could lose 2 points from two stats and D6 from the other TWICE off one injury event, plus a resulting injury crisis.
And Merchants are not one of the better careers as far as Cash payout goes - three rolls without Gambler skill gives an average of Cr48,000. Some players may choose to start in debt in order to maximise their Other Benefits table rolls... what's a piddly Cr30,000 medical bill vs even one ship share?