Election Betting Markets, Again

Maybe someone can tell me why we get such different bets depending on the platform (and why RealClearPolitics doesn’t include PredictIt)?

First, an item that arrived in my mailbox this AM from OddsChecker in the UK.

Compare with RCP:

All of these covered by the RCP have very strong probabilities.

Then there is PredictIt, which is very close to OddsChecker.