Frankly Webtoons should not exist. It is a financial loser. No income (ads are coming at some point) and tens of thousands being paid out to creators each month, not to mention the fixed costs of servers and staff.
Webtoons is completely dependent upon Naver Corporation to stay alive. Naver is the Korean equivalent of Google. They financially support Webtoons because it promotes their platform. It's like selling white bread at a loss to get customers into your store ("loss leader pricing"). However Naver could shut down Webtoons at any point in time and from a CFO's position it makes complete sense.
So yeah, as great as Webtoons is, it is a house of cards propped up by Naver. There's a chance Naver may never pull the plug, but if it does, it will all disappear overnight (e.g. Inkblazers) since there is no way it can stand alone on it's own. Naver has already taken one step that shows a slow withdrawal of support, they spun-off Webtoons into its own corporation last year.
By no means does this mean Webtoons is on fire and today is the end of the world for them. Creators however just need to keep their eyes wide open and prepare for all possible outcomes. What we eventually may see is Webtoons transition into a subscription model because ads alone won't be able to support it if Naver decides to step back.
Ad revenue is experiencing a death spiral. Recently Anime News Network has resorted to asking for donations like Wikipedia.
"Advertising is no longer enough to support Anime News Network entirely. While some of our advertisers have remained very loyal to us, others have their own challenges and have no choice but to cut their budgets. This, combined with ad-blocking and dropping CPM rates means that, while it costs more than ever to operate Anime News Network, it's now harder than ever for us to finance our operations."
https://www.animenewsnetwork.com/subscription
Readers aren't clicking ads and are even blocking them outright, resulting in producers of content struggling to stay afloat. Whatever income Webtoons is expecting from ads won't likely be long lived.
Ad blocking is growing by 30% year over year. According to an IAB report, 26% of all desktop users and 15% of all mobile consumers use blockers to remove ads from publishers' websites. Those numbers are only going to continue to grow.
Free readers will eventually kill the goose that laid the golden egg.
Smackjeeves is run off ads, so eventually it too will go the way of the dodo.
This is why Tapas is working hard at trying to build a sustainable platform for both creators and readers. They offer voluntary ads for readers to watch and creators get 85% of that when tipped. It's fair. They need that 15% in order to keep the company not only online but improving. As pointed out earlier, Amazon is taking 30% on eBook sales. In light of that, Tapas' fee schedule is reasonable.
If you are buying coins from Apple/Google then you have to take into account that Apple/Google has their own cut. So you have two parties involved in the transaction, not one. This is why you're seeing up to a 45% transaction loss. The way to reduce those fees would be to tell readers to use web tipping, buy discounted Apple/Google gift cards, or save up and make massive tips during Tapas' next Tipping Event.
Yes, during the tipping events, Tapas loses money. They've paid out 20% back twice and could pay up to 30% if the top tier is ever reached. This is a 5% to 15% loss for the company. Their loss is creators' gain.
If you want to support a creator with no fees then you'll have to mail them a check which has the cost of an envelope and postage, so even that's not free. You can use Patreon but that has a fee. The creator can open a merchant transaction account and accept credit cards but that has lots of fees and a lot of paperwork and annual compliance requirements. You could "send a gift" on Paypal and if you are both in the United States, then yes, that would be transaction fee free.
But what creator would want to take the time to process thousands of $.02 to $.04 tips via PayPal? Your time is worth money, so all the convenience of Tapas collecting your tips for you and sending one payment is time saved. Consequently they charge for it, 15%. Wouldn't you if you were doing that service for someone else?
The "flaws" that Tapas has (Premium Comics, Tipping) are actually a predictive response to an almost certain future where ad revenue cannot support most websites and many have no choice but to close down if they cannot self-fund their activities.