This is really an example of hiring someone who has experience and hiring someone who thinks “it’s easy and just like what I did before”.
Then I could get into all of the old netops guys who think AWS is just like what they did on prem and end up costing the company more...
Website backends often have significant dependence on other services that can be down. Further standalone apps can have zero network dependence or a lot. So having written both, and similar code for each, I don’t feel the networking side is all that different.
If anything networking is probably the largest similarly between them.
PS: I did some iOS development in my spare time even worked with some old J2ME, so I assume Android is fairly similar.
That's changing with the advent of progressive web apps. It's possible to write web apps now that are robust in the face of network problems, e.g., the web app renders and is functional even without a connection.
I started with Object Pascal on Mac OS 8/9 which forced you to do a lot of low level tasks like deal with Handles and suffer through a cooperative multithreaded OS. Rewriting the network layer from AppleTalk to TCP/IP was closer to systems programming in C than you might think.
I have also been paid to write C programs, Windows application pre .Net in Visual C++ and post in C# and VB, written Java and C# websites, and most recently Angular SPA’s. Add to that a few random oddities like XSLT.
PS: I even turned down working on Android, but could have made that jump.