Drug companies funneling money to politicians on the sly,
to make sure that drug prices stay high.
Another reason to go with proportional representation. If you can select who represents your interests out of ALL of the possible candidates, you can select someone that is commited to your agenda.
And if your elected representative understands that you'll switch your support to someone else if he or she fails to stick to that agenda, it becomes very difficult to sell his vote to the highest bidder.
And that candidate doesn't need as much campaign money to try to convince EVERYBODY to vote for him. He or she just needs to make plain his or her views and then convince those that share that agenda that he or she can move that agenda forward.
That doesn't mean that the drug companies won't have their interests represented. Their employees and shareholders can all vote too.