As a matter of fact, these publishers/databases, have different policies and at the same time do not share a common platform/method/topic...even different from one journal to another one in a given publisher. for examples the ones in medical sciences may choose different manual of style from social sciences...
In days of print and paper I mean before Internet and emails we had to do it manually. Then post it to the journal address. A good thing to think about is, to visit the web page of your target journal and read IFAs (instructions for authors) carefully.
Also to make it very easy, they have their own platforms for authors. As far as we are engaged, when a person signs up as an author on website of a publisher, then almost every thing has been ready well-cooked. Menu after menu and step by step you enter data they have asked, also when needed they have left a good room in each step to add other notes you think important and then upload your manuscript, review all and if you need to correct what ever you want do it and then click.
I urge caution as Rahim Alijani has also mentioned. Different journals have different expectations and while I agree with you that this step is time consuming, I have found in my own experience that you often have to spend some extra time with each journal and cover letter to make it sufficiently individual and specific enough to meet the needs of that one specifically. It would seem very nice to have one that fits all situations but we really need to be cautious about this approach and try not to upset journals and editors to improve our chances for our articles to be published.