Any #bookkeepers out there?

In Chile, bank transactions are instant. Why is it that I can spend received funds instantly but my bank still sorts transactions per day in increasing order of value? So lets say my balance was zero, I get 10 and send 10. My online bank statement reads this as me overdrawing my account by 10 before neutralizing it. And if I get 10 spend 10 for 5 times, it shows my balance go down to -50.

Now if any actual Chilean contadores are listening ... I actually wouldn't mind switching.