Take it this way:

If they hire you, relocation is part of that process, and the money is spent worthy. But if you are only there for an interview, that trip they pay could be wasted. Without a good reason to reject your request, you throw the ball to you. If you are confident to get that job, you will take relocation offer; otherwise, when you take the tickets, they might want to re-consider:) BTW, what if they are really cheap, that the relocation package is just a return ticket?

100 Best companies or not, each firm can find to be good at some categories. That's just useless spin.