Just spoken to SCB here in Central Mall, Pattaya. They seem aware of the income from abroad issue and will issue the necessary letter for immigration showing fund transfers from abroad into your SCB bank-for a small charge. I can only assume other banks aware.
TLDR : Answer Summary
A recent inquiry at SCB in Pattaya revealed that the bank can issue letters for immigration showing foreign fund transfers, though there is a charge. The community discusses the reliability of such letters for visa applications, mentioning experiences with other banks and expressing concerns over whether immigration will recognize these documents.