Many Numeric Fields Processed as Text - Intentional?

[BinaryPaean]

I probably misunderstand something about Singer, but many numeric fields are processed as text. For example: order_adjustments.tax_amount, order_adjustments.amount, customers.total_spent. A few of these have been annotated with:

"format": "singer.decimal"

But many have not. Specifically I have noticed that customer.total_spent comes through to my PostgreSQL endpoint as a text column, which is undesirable for attempting to segment customers.

Is there a reason for these fields to be text? If I create a PR that addresses it, is it more correct to update the type to "numeric" or to update the format with "singer.decimal"?