Commas in quotations

"What is your business here?" he asked.
"I am taking my domestic home," I said, surprised at how calmly I lied.
He peered at the children sleeping on the back seat. "Where does she live?"
"Fifty-seven," said Florence.
"You can drop her here, she can walk, it is not far."
"It is raining, she has small children, I am not letting her walk alone," I said firmly.

the above is an excerpt from J. M. Coetzee's Ageof Iron. My problem is with the commas (in bold typeface) which are used at the end of dialogues. In the second-last line however the sentence is ended with a full stop, so the usage of commas is intentional.

Any suggestions???