Given that student evaluations are crucial to most professors’ tenure and raises, it’s in their interest to give out good grades. So your very premise - that professors “like to give bad grades” is wrong.
And consider grad school: any university where “As” are easy to come by will be known for grade inflation. And there’s nothing worse than having your hard-earned As - or A-minuses - suspected of being padded.
Be glad you have the demanding professors you have. It means they have integrity - and standards. Grad schools appreciate both.