Head-to-head, with sources.

Traditional card processors optimize for a merchant profile the average high-risk operator does not match: sub-1% chargebacks, low-refund verticals, MCCs approved by every issuer. When operator reality diverges from that profile — as it does for iGaming, adult, nutra, and gray-zone verticals — the model breaks in predictable ways.

The pitch is simple: 'we take verticals Stripe won't touch, at higher rates.' The reality is that offshore acquirers still route through Visa and Mastercard, still trigger VAMP and MATCH, and add rolling reserves that are roughly 2x what a US-domestic high-risk MID would charge — for a counterparty with materially higher freeze and exit risk.

Stripe's Restricted Businesses list is one of the longest in the industry. iGaming, adult, cannabis, CBD (except in narrow permitted states), peptides, kratom, firearms, debt relief, most nutraceuticals with health claims, and 'high-chargeback' MCCs are categorically excluded before the underwriting conversation begins. For the merchants who do clear onboarding, TOS 5.k reserves Stripe's right to hold funds up to 120 days after last activity — and enforcement of that clause is well-documented.

Authorize.net (Visa-owned since 2010) is a gateway — it routes transactions to whatever merchant account you're boarded on. For high-risk operators, that acquirer relationship is where every real constraint lives: reserves, chargeback thresholds, MATCH exposure. Authorize.net's own AUP echoes Visa's restricted-merchant list, so high-risk verticals either can't use it or can't find an acquirer that will pair with it.

PayPal is two products stacked: a card processor and a captive-wallet system. Both come with the widest cardholder-protection windows in payments (180 days for buyer claims, up to 20 days for chargeback representment), unilateral hold and reserve powers under User Agreement Section 10, and a categorical Acceptable Use Policy that excludes most high-risk verticals. Operator complaints about PayPal-initiated 180-day holds are documented across the FTC, BBB, and every consumer complaint aggregator.

Checkout.com is a UK/EU-licensed acquirer with strong European market share and enterprise reputation. Its published acceptable-use documentation is one of the more explicit in the industry — which is helpful for compliance clarity and unhelpful for anyone operating in a listed category. Gambling requires jurisdiction-specific licensing and Checkout-specific approval; adult, cannabis, and most binary-options and forex categories are prohibited outright.

Nuvei (post-2021 SafeCharge / Pivotal Payments consolidation) is one of the loudest high-risk-friendly acquirers in the market, boarding iGaming, forex, and adult merchants that Stripe and Adyen won't touch. That willingness comes with the reserve, fee, and termination-notice terms typical of specialty high-risk acquirers — plus the shared VAMP and MATCH exposure of any card-network processor.