Fans attending Adelaide Oval for the first AFL qualifying final tonight will face a challenge if they're wanting to pay with cash for food and drinks inside the taxpayer-funded stadium.

The oval this year converted a large number of outlets to only accept card payments.

It's a move Adelaide Oval Stadium Management Authority (AOSMA) general manager Darren Chandler said was all about faster service and followed a trial for card-only outlets during the 2016-17 cricket season.

"The trial was well received, particularly by those seeking a faster speed of service and for the growing number of patrons who do not want to carry cash," he said.

"Approximately two-thirds of our outlets are [now] card-only, which is slightly behind buying behaviour where card transactions sit at around 87 per cent."

Adelaide Oval has a busy weekend of football finals, starting with tonight's clash between the Adelaide Crows and Greater Western Sydney.

Port Adelaide Power take on the West Coast Eagles on Saturday night, while on Sunday Sturt will play Central District in the SANFL semi-finals and Woodville-West Torrens will play the Port Adelaide Magpies.

Patrons have reported having to walk a long way to find a cash outlet.

The oval also offers a small number of booths where patrons can exchange cash for a food and beverage cash card, but they are an added inconvenience for those trying to get fed and watered and return to their seats in the rush between quarters.

Australian Privacy Foundation chairman David Vaile said card-only payment systems in general were a "straight-out" attack on anonymous payments.

"There's the old furphy, 'if you've got nothing to hide then you have nothing to fear'. It's complete nonsense," Mr Vaile said.

"You've obviously got something to hide — PINs, bank details — and it's not because you're criminal but because you're sensible."

The Crows kick off the 2017 AFL finals against GWS at Adelaide Oval tonight. ( AAP: David Mariuz )

Crows supporter Sam Auld is a regular visitor to Adelaide Oval and suggested the stalls might lose business from time-poor punters as a result of card-only systems.

"Many people wouldn't want their partners knowing how many drinks they buy and how much they spend. It's easily avoided with cash," he said.

"It's all about cost saving for them; no tills to count, less chance of mistakes and theft, and payWave is faster than cash."

Mr Chandler said all credit and debit cards were accepted and transaction fees were absorbed by AOSMA. The cash exchange cards incurred no fees and could be reimbursed in full at any time.

He said he did not consider the system to be a threat to consumer privacy.

"Consumer behaviour is trending this way and it's all a part of our approach to keep up with consumer demands and provide a faster service for patrons."

Card-only systems could be used for surveillance

Mr Vaile said commercial transactions had not been an obvious government surveillance mechanism in the past because the effort required was intrusive and largely unjustifiable.

"But with the increased reach of the real-time financial tracking systems, at some stage it may become accessible without a warrant," he said.

"There's a problem in that the bar is constantly being lowered and the capacity [for tracking] is being raised."

Mr Vaile added that people often did not realise that it was not just about them.

"If, for instance, you're tied to a particular transaction to a particular venue and other people turn up in the same place, that enables network analysis.

"You were there with your mates. It might not be a big deal, but on the other hand it is becoming increasingly difficult to protect that information."

He said there was a global push to recognise that anonymity was a legal right and the "starting point" for privacy protection.