Exactly. I'd go further and say the burst capacity is actually a super useful and powerful feature that is very hard to get on your own hardware. Definitely can catch you unaware if you aren't on top of it and can get expensive for some needs, but as you say not hidden at all.

I have a hacky shell script I sometimes use for moderately sized environments that don't have better monitoring setup, it reports the minimum percent of burst balance remaining over the past day, requires the aws cli and parallel:

  #!/bin/bash
  while getopts "p:" opt; do
    case $opt in
      p)
        export AWS_PROFILE=$OPTARG
        ;;
      \?)
        echo "Invalid option: -$OPTARG" >&2
        ;;
    esac
  done

  if [ ! "$AWS_PROFILE" ]
  then
    echo "-p <aws profile> or AWS_PROFILE env var required"
    exit 1
  fi

  start=$(date -v-1d +%Y-%m-%dT%H:%M:%S)
  end=$(date +%Y-%m-%dT%H:%M:%S)

  aws ec2 describe-volumes --output text --query 'join(`"\n"`, Volumes[*].VolumeId)' | parallel -j 20 "echo -ne {}\\\t && echo \$(aws cloudwatch get-metric-statistics --start-time $start --end-time $end --period 86400 --namespace AWS/EBS --statistics Minimum --metric-name BurstBalance --dimensions Name=VolumeId,Value={} --output text --query 'Datapoints[*].Minimum')" | sort -n -k 2