In message , at 16:49:52 on Sun, 4 Mar 2012,
Stephen Sprunk remarked:
There's always a small risk, and sometimes the ticket vendor will make a
[mobile] phone call if a particular cardholder raises suspicions.

If mobile service is available, why not just authorize every card and
avoid the risk of being sued for discrimination--which will cost far,
far more (even if you win) than losing the occasional fare?

Because authorising transactions with a voice call is time consuming,
and may not even be possible as a routine thing.

and people with credit cards and bank accounts that allow overdrafts
usually do pay these off, the only class where there's a serious worry
is the no-overdraft debit card holders.

Some of our debit cards allow overdraft, while others don't; that is an
option by the account holder.

In the UK an overdraft is a property of the account, not the card. In
the US, can you have a bank account that allows an overdraft if you
write a check, but a card that won't allow that same account to go
overdrawn (I could see some uses for such an arrangement).

There is no way to know by looking at the card number whether it does.

That's what we *could* do in the UK, by recognising a card as "Solo" or
"Electron". Now that they are branded as "VISA debit", it's probably not
possible to tell, although the cards are still incapable (in theory) of
pushing the bank account into overdraft. What we haven't established in
this conversation yet is how the banks achieve that Indian Rope Trick if
people buy something from (eg) a vending machine that isn't online.

Given the cheap and ubiquitous mobile data networks, there is no excuse
for not being able to do online authorization.

They aren't cheap and ubiquitous enough. In particular, the equipment
would need replacing (not just simple upgrading).

It gets replaced every few years anyway, and the cost of adding mobile
data to them should be trivial.

It doesn't seem to work like that. The current machines are relatively
new, dating from 2006. The previous generation of machine lasted almost
20 years in service (1986-2006).

I don't believe data
networks are ubiquitous in the USA either, if the very spotty mobile
phone coverage more than a few miles from major cities and highways is
anything to go by.

The main problem in the US is multiple incompatible networks, and it
should be better overseas where everyone uses GSM. Still, US mobile
coverage is pretty good; even a decade ago 96% of the US population was
covered, and nearly all Interstate highways are. Rural areas and lesser
highways are being covered rapidly, as would rail lines if a non-trivial
amount of passenger traffic existed.

That's not our experience in the UK, where people are famous for making
calls "on the train". Coverage is often very bad, despite percentage
rates appearing high because areas of high population are flooded, and
places where people don't live (highways and railways lines) get
neglected especially if the geography is against them (tunnels,
cuttings, valleys etc).
--
Roland Perry