Regarding the legality of this in the US...
Minimum amounts used to be forbidden by credit card companies in the US, but there was no federal law around it, and so many smaller retailers used to regularly set minimums on consumers. Consumers could call the credit card companies and report those retailers, but most people do not, and even if they did most CC companies didn't bother penalizing the retailer though they could have. In 2010, the Dodd-Frank Wall Street Reform bill set a federal ceiling of $10-minimum throughout the country, which forbade credit card companies from preventing retailers from setting a minimum up to $10 (and law also had other restrictions, like no minimums allowed on debit purchases and every CC has to be treated equally so you can't require a $10 minimum for Visa but $5 minimum for Mastercard). What this means is that retailers can set a $10 minimum on credit card purchases, but nothing higher than that. Today most retailers have no minimum for credit card purchases and it's becoming less common, though you still typically see this at smaller, independent or franchised retailers. In the real world for instance, I buy most of my groceries from a major super market that has no minimums, but I buy my dog food from a small grocer/general store that has a $5 minimum for CC purchases.
Prior to Dodd-Frank this was regulated state by state, with most states either having no regulation on it or having a $10 or lower rate. Credit Card companies strictly forbid minimums for retailers, and retailers who set minimums -- prior to 2010 -- were supposed to be reported to the credit card agency. Now, CC companies have to respect retailer minimums, but no retailer has to set a minimum... It's completely optional. It can be argued if this is anti-consumer or not... From a consumers perspective, having a $10 minimum to use a CC seems anti-consumer, but the argument from Dodd-Frank is that this protects small retailers from multi-billion dollar credit providers dictating their business, which ultimately (as the argument goes) helps consumers by protecting small retailers.
This could very well vary from state to state. The OPs $10 figure makes sense federally, that is the US federal ceiling for minimum purchases for credit card transactions. But it's extremely rare, like virtually non existent anymore, for online retailers to require a minimum payment to use a credit card... It was more common 10 years ago, before Dodd-Frank and also when online retail was also much smaller than physical retail. This usually manifested itself in the form of gift cards, points cards (Microsoft Points were usually only sold in amounts of $5 up until like ~2010 when Microsoft got rid of the MS Points system), or virtual currency (think, Rocket League keys, microtransactions for in game perks, 2K SPorts Virtual currency, EA Sports Ultimate Team packs, etc).
One thing is for certain, Sony is not a small retailer. The optional $10 ceiling for minimum transactions by US law is made to protect small retailers. Major businesses using this to require minimum payments for something is certainly anti-consumer, though it's still protected under law for the retailer to do that, it's just a shitty, unnecessary thing to do for a major retailer.