Dart Unhandled exception: NoSuchMethodError: Class '_InternalLinkedHashMap<String, int>' has no instance getter

Please help me understand why this sort doesn't work. I've read Dart's documentation several times and it's just not clicking why this doesn't sort how I expect it to.

void main() {
  final hand1 = {
    'ranking': 1,
  };

  final hand2 = {
    'ranking': 2,
  };
  final hand3 = {
    'ranking': 1,
  };

  List players = [hand1, hand2, hand3];

  players.sort((a, b) => b.ranking.compareTo(a.ranking));

  // Expected players to become
  // [hand2, hand1, hand3]
}

Dart complains:

Unhandled exception:
NoSuchMethodError: Class '_InternalLinkedHashMap<String, int>' has no instance getter 'ranking'.
Receiver: _LinkedHashMap len:1
Tried calling: ranking
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:38:5)
#1      main.<anonymous closure> (file:///Users/primetimetran/Desktop/projects/flutpoke/poker_class.dart:15:28)
#2      Sort._insertionSort (dart:_internal/sort.dart:69:36)
#3      Sort._doSort (dart:_internal/sort.dart:58:7)
#4      Sort.sort (dart:_internal/sort.dart:33:5)
#5      ListMixin.sort (dart:collection/list.dart:356:10)
#6      main (file:///Users/primetimetran/Desktop/projects/flutpoke/poker_class.dart:15:11)
#7      _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:297:19)
#8      _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:192:12)

I lack an understanding of how the internals of Dart work I know.

Thanks in advance~!