I got what I thought was an excellent question on Reddit the other day and thought I’d post my reply here too. Rather than tidy up my answer (which seems unfair) any this is exactly as it is on Reddit.
And my answer:
Great question! There are a couple of points to this;
Firstly; Simple PoS does indeed use a local cache database on the device; this allows for use in offline situations and also makes the whole application faster and more responsive than a cloud only based system. Being local only would on the flip side not allow multiple devices without more difficult setup. which brings us to:
Secondly; Simplicity. Micro and small businesses don’t necessarily have the kind of IT resources to setup their own databases, be they local or Cloud based. Everything about Simple PoS is aimed at simplicity from the initial single click install and setup to the Store IAP purchase which removes any external or separate sign up process (it’s as easy as buying “coins” in a game).
Finally; performance. The other main competing option from using Azure style cloud services on Mobile devices (tablets, phones or laptops) is something like a SQLite database which sync’s with another database in OneDrive or something like that.
While this method works, it is not performant for high throughput applications on multiple concurrent devices. The way around this would be to have infrequent syncs (say; daily) but then you have not got access to live data where ever you are and also it leaves many opportunities for data loss if anything happens between sync’s, which I find simply unacceptable in a Point of Sale application.
As a final note; Simple PoS did have a first iteration where it was a single device system using a local DB only. When we started cleaning the idea out it seemed limiting and also didn’t offer the kind of compelling business case that I wanted. Im not saying that it’ll be for everyone, nothing is. Some will want all local, some will want multi users, some will be against cloud, some for. Choice is Good!
From what we saw in the market we wanted available anywhere, multiple user access which was so simple that anyone can do it. So that’s the direction we took Simple PoS.
Edit; missed one! Azure and similar cloud services allow true cross platform. If we take Simple PoS to Android and iOS, Azure can do this with zero fuss. OneDrive and other personal file storage options this is not so easy. Plus it requires everyone who might use the system to have access to your OneDrive file storage (eek!)