Personally I don't think the level of hold is fair, or commensurate with the risk in the average case. I almost always have my travel booked via some site like tr@vel0c1ty, etc, so the entire rental is already paid for. Yet a 200-300 dollar hold is always placed on my credit card, even after customer service stating explicitly that no hold would be placed in several cases. So are they just trying to cover the potential loss of rental revenue there? Even more interesting, I have had rentals booked on corporate travel cards, and still had to pony up my own cc, which a large hold was placed on. So in both cases they are abusing the consumer by having two forms of security, and who cares if the business traveller or vacationer gets the shaft since 50%+ of their balance is now on hold(again, remember hotels, etc. also want to do this, even when the room is pre-paid). Many consumers are unaware of these holds, since credit was given much more freely in the past, however, some consumers feel that pinch desperately and the rest should be aware, and asking why.
This is an industry wide practice, and consumers with 'low' credit balances are shamed by others into not speaking out. I have a low credit card balance, but this is only relative to the insane amount of uncharged holds placed by various companies. If I burn the car and leave it in a ditch a) I will be arrested since they have taken my identification, and potentially know what plane I left on, and b) there is an insurance industry to offer coverage for business losses, which is also posting profits despite all the masses of people burning cars and leaving them in a ditch, you've heard about them all on the news, right?
No, you haven't, because it just doesn't happen that often. Remember, you are looking at a picture of large scale with these companies, so a company may have this happen 200 times per year, which a whopping lot of money;however, how many total cars are in the fleet and profitable, what percentage of total losses are there, and how much is covered by their insurance, and accepted as a normal risk level for their policy? You will never begin to get answers to these types of questions, only expressions of a portion of the picture that serves someone's current purposes.
Do not be fooled, these are large corporations with no concern for consumers, beyond keeping them buying. They will charge whatever they can get away with(look at the definition of a corporation, it is an entity to make money, not get into heaven or do good deeds!). They are pushing their cost of doing business back onto the consumer in an ever spiraling attempt to increase the bottom line(each generation of upper management has to make their mark right?). They will continue to do this until there is push back to the bottom line through lost revenue, that's just the nature of the beast.
Until consumers find an alternative, or our country in general gets reasonable and safe mass transit(I am not holding my breath there at all), they will continue to increase those margins on the backs of the consumer, and hide behind 'policy', smoke, and mirrors.
The real question is what is the opportunity cost of the hold for the consumer, and that is inversely proportional to their available balance.
Personally, I have had to opt for taxis on several trips due to the excessive holds. To be honest, I really don't mind it that way, no 30 minute drive after an 8 hour flight, just off in a cab and you're at the hotel.