Without additional context, my assumption is that since all the values are null, it's impossible to determine the column's type. Do you have a default value? You could consider coalescing with that value. For example, if the default value is false:

SELECT 
  SUM(
    CASE WHEN COALESCE(
      CAST(match_result.ecommerce.has_online_payments AS BOOLEAN),
      FALSE
    ) THEN
      1 
    ELSE 
      0 
    END
  )
FROM
  parquet.`s3://folder_path/*`

Otherwise you can handle the null values as @Retired_mod suggested.