It's perfectly legal (and common) for a decade now to scan documents and destroy the paper original as long as you follow some guidelines. Keyword is "ersetzendes Scannen".
And yes, they care about those rules and that you provide "originals" according to that definition - in particular that you didn't modify digital documents in any way. You can (and should) comply with that and there are service providers to help if you are to small to set that up yourself.
Thanks, today I learned about "ersetzendes Scannen". I just checked and it's exactly a decade (2013) since it's allowed which coincidetally is the year when I started working as a freelancer (and I have to care about such rules).
I admit that my last paragraph was kind of hyperbole, but I never heard (at least from other freelancers) of a tax inspector which wasn't happy with either everything printed or everything digital. I guess they really start to care if they suspect something fishy.
You already agree to buy such an ticket (at the "erhöhtes Beförderungsentgelt" price) but there is no way to avoid a criminal law specifically designed for that situation by just changing the content of a contract.
The linked tender is mostly not about marketing. They tendered basically a pretty large travel agency. Eurail is surely not just a intermediary here. They are in the business of selling train passes and operate lots of the services tendered for decades (e.g. an online train booking platform)
But the same publication says that only a bit over 50% of the population even own a credit card. And debit cards usable online are still a niche product.
So in Germany, can you pay your Paypal bills any other way than by credit card? Honest question, when I lived in Germany the last time, Paypal did not exist yet.
Germans are usually very aware of hidden costs and credit cards are usually more expensive per transaction.
Germans also usually are much less in debt than for example many US citizens - for example the University education costs much much less. Young adults have 1400 Euros (plus!) on their giro account and it is typical to pay from that account.
The usual method is by SEPA direct debit (initiated by Paypal) but you can use a SEPA transfer as well to top up your Paypal balance and pay with that.
Ah, I had no idea that Paypal would do SEPA direct debit . They don't offer it to me. (I don't have a German address, although I would have a German account.)
Employees in high salary groups can opt to get a "NetzCard" which allows unlimited travel in all DB operated trains. High management gets a real BahnCard 100 for them and a second person.
The free day tickets for private use that every employee gets are limited to 16 a year (but only one a month is tax free) and don't allow to take someone with you.
By the way, not every employee can use first class for business related travel (many can).
It does not have such a service. In fact, it is prohibited to use the document number for any other purpose than identifying the document itself, even for government entities.