This means that these e-pays wallets vary from country to country, and we may not be able to use them worldwide.
True, it varies and operates locally.
BK8 has to setup support for many e-wallets of different countries in order to activate this service. This might be a big hassle for them.
Not really, there will be a 3rd party company that act as the payment processor, so BK8 just use their services. For example, for ID region deposits, they use Pay4Me & WEPAY, via this service you can deposit from any e-wallet here. I can imagine that they'll use another 3rd party company for withdrawal that supports the majority of e-wallets.
Perhaps we should not forget that all payments in fiat currencies are controlled to one degree or another by the central banks of different countries and a whole group of various regulatory and tax authorities.
And in each country, the laws of this country, aimed at such regulation, have been adopted accordingly. And breaking laws is usually quite risky, and from serious organizations and firms and legal entities in general, usually no one runs the risk of doing this.
Yep, if you play from countries that prohibit online gambling, crypto is a much safer option. But keep in mind that there's a hassle to go in/out of exchanges and there are fees and minimum withdrawal associated with it. The good thing is, users can choose whether the risk is worth it for the cheaper fiat option. For example, the police may not bother you if you gamble only $20 privately.