It could also be "normal". The 2 Billion reads is trivial on large systems especially if there's a lot of batch processing. SQL Server can't do a thing with data unless it's in memory. Some folks' goal is to have enough memory so that the whole database can live in memory which would mean that almost everything would be logical reads and very little would be physical.

Of course, it could also be because of the things you say or it could be just crap code. It could also be from regular rebuilds or reorgs of large tables, which is a "normal" thing, as well. The overall number of reads means very little unless you can identify the source and then the cause of those reads.

I'll emphasize the crap code possibility because I've regularly run into single procs that generate tens of billions (read that as tens of Terabytes of I/O) of reads either in a single run or in multiple very short runs that occur 10,000 times in short periods of time. All of those can be fixed.