OT When a merchant, such as a rentacar company, puts a hold on one's
money and doesn't end the hold for a month or more,

a) Does the merchant actually have the money, or is it only reserved for
him at your credit card company?

One indication of this woudl be, I suppose, if you are paying interest
on it.

b) Why does it take so long? They can tell as soon as you bring it back
what most of the damage is, and after putting it on a lift (do they do
that?) what damage there is to the undercarriage. They know as well as
any body shop what it costs to fix this stuff or are they expecting to
find more damage during the repair?

That only applies if there is damage. Do they have some standard rule,
45, 60 days whether there is damage or not?

c) In some places bills for illegal parking take iiuc more than 90 days
to come in, because whoever originates those bills waits until the
driver sends in the money. When he doesn't, they send a bill to the
owner which is the car rental company. I suppose illegal parking bills
could be pretty high. Do they release the hold before the 90 days are
up, and then charge the same credit card later anyhow? I suppose this
varies but any known examples would help.