As a Brit I'm Deeply Unsurprised by the Blackwood family's shitty everything but also interested to hear of their existence as Hereditary Magic-Users By Appointment To The Crown. Do other present-day countries in this 'verse have a similar position-Court Wizards, whether to actual monarchs or to governments or heads thereof appointed by other means? If so, does Japanifornia have someone in that position?

After a certain level of wealth, power and/or celebrity status, it's a matter of course to contract a professional mage, like hiring a PR Manager or a Finance manager. Pretty much every Head of State, Billionaire, and Movie Star has used the services of a Mage.

New Zealand was the first state to make "Offical Wizard" an elected position, but other states consider the Wizard part of the head of state's cabinet, and others have lifetime appointments. The extant Monarchies of the world all have royal wizards, but England is unique in having a hereditary family of wizards (most monarchs appoint a new, unrelated related wizard at coronation), and this is because every monarch since Queen Elizabeth the 1st is in Major Hock to the Blackwoods.

It's also worth noting that when Seto Kaiba says he "doesn't believe in magic", that's not because he doesn't think it's real. He just thinks it's weird to "Believe" in, because that's like Believing in the post office or JavaScript. It exists, it's a tool, and he has people to handle it. Lots of people. Way more people than most comapnies employ because kaibacorp used to be a military weapons company and is the target of SO MANY curses. So he's got a small army of cursebreakers under contract to get those removed, often by tracking down the original caster and making repairations for whatever Gozaboro did, because that's the most cost-effective way to handle them. And the right thing to do. Even if Seto will never say that part aloud. He's also got tech wizards to keep the server farms and other machinery from developing thaumaturgic properties and appease the machine-sprits that inevitably arise with any computing operation of that scale. And Illusionists working in the art department to make his monsters that much more convincing. And of course, a full staff of White Mages and other necromancers on staff to act as emergency services at Kaibaland. Like IRL Disney, nobody dies at Kaibaland. Unlike IRL Disney, he doesn't accomplish this by playing silly buggers with the coroner's office. When he says Nobody Dies At Kaibaland, He Means Nobody Dies, No Matter What.

Maximillion Pegasus is an oddity for not employing more wizards than the usual Corporate Cursebreakers, but that's hardly surprising considering how territorial mages are.

Lots of celebrities employ illusionists to cast anti-paparazzi and stalker wards, and the really rich ones pay for top-notch illusionists and even chronomancers to try to preserve thier youth.

There's also a lot of mundane and municipal wizards- Bakura has a part-time job hunting for magically charged or cursed objects at the city flea market to prevent the sale of dangerous magical items. There are also tech wizards that maintain the city sewage treatment center or the machines that sort recyclables from garbage. You'd think there would be wizards to cast "Zone of Truth" at courtrooms, but that turned out to be functionally useless- witnesses STILL gave wildly conflicting versions of events, people who definitely commited the crime pleaded still their innocence, and Lawyers still made completely unhinged arguments, because everyone was absolutely sure they were being honest.

There's also magic-adjacent jobs done by people who aren't mages, but who have a sense for the stuff, like Tristan's family, which would be monster hunters/dungeoneers in other settings, but in TPOFATGIF, they're just Advanced Pest Control. Or Solomon's old job as an archeological tomb-crawler, where he used his sixth sense to sniff out undiscovered (and very cursed) archelogical sites and work out what the curses are backwards from how the tombs and temples are built.