It is indeed an issue if Apple Pay is ultimately accepted via an app. If we have to download an app for each restaurant or other business we visit, we're going to fill up our devices with hundreds of apps and slow them down.
If you go to a particular restaurant often enough, it might be worthwhile to download the app. If not, Apple Pay is still supported via Safari, even IIRC on the iPhone.
Besides, using an app is a more limited approach that eliminates the option for restaurants to be able to accept forms of contactless payment that can't be used in-app such as Fitbit Pay, Garmin Pay or even contactless cards.
Supporting Apple Pay via an app or website doesn't preclude anything else. That'd be like saying that stores aren't inclined to support AP because Samsung Pay already works without having to upgrade.
In fact, by supporting the Payment Request API on a website, it's trivial to support all of the mobile wallets that have Web support. Though since the big three (Apple, Google and Samsung) have far more use than the others, those would be the most logical ones to support.
Furthermore, the habit of taking away a customer's card to process a payment is a giant security flaw and needs to be eliminated entirely, not just optionally.
If the vast majority of people eventually end up paying with the restaurant's app or website, doesn't that achieve the same thing?
(can't believe Americans aren't worried about this, how naive).
Adding extra tip for yourself is something that will be caught extremely quickly. Not to mention that POS systems know exactly who served what table at what time, so the culprit is easily found.
As for just copying down the card details, I suspect that fraudsters get far more ROI from installing skimmers at gas stations/ATMs and installing POS malware than having individual servers risk jail time.
As for the tip adjustment, the portable POS devices such as the ones I previously sent pictures of have an option called sale with tip, which allows to enter both the check amount and the tip before the card is inserted or the mobile device is tapped so no tip adjustment will be left to be made later (and the devices even offer some standard options to automatically calculate the tip such as 10%, 15% or 20%).
Again, something that can also be done via an app or website.
Look, I'm not saying that having to use an app/website for pay at the table is ideal. Ideally we'd have wireless devices, or at the very least have people paying at the front. Apparently that's not in the cards for most US restaurants, however, so something that will enable similar functionality relatively quickly without having to convince them to replace their new terminals literally months after installing them is a plus. Who knows, maybe there actually ends up being enough demand via the app that some restaurants decide to take a chance at making the rest pay at the front or something.