Mongodb – nodejs handling callbacks in promisses

I am tying out node.js, but not able to wrap my head around why one works and other doesn’t

can you explain to me why
this works:

 app.delete('/notes/:id', (req, res) => {
        const id = req.params.id;
        const details = { '_id': new ObjectID(id) };
        db.collection('note')
        .deleteOne(details)
        .then((result) => res.send(result))
        .catch((err) => {
          !error.logged && logger.error('Mongo error', err);
          error.logged = true;
          throw err;
        });
      });

but this never enters the callback function and gets stuck in deleteOne, but in db we see entry is removed

app.delete('/notes/:id', (req, res) => {
        const id = req.params.id;
        const details = { '_id': new ObjectID(id) };
        db.collection('note').deleteOne(details, (err, item) => {
          if (err) {
            res.send({'error':'An error has occurred'});
          } else {
            res.send('Note ' + id + ' deleted!');
          } 
        });

also all examples i see , they say below code should work but it never enters callback, it does make db connection i can see in db logs

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
console.log("hello");
MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  var dbo = db.db("mydb");
  var myobj = { name: "Company Inc", address: "Highway 37" };
  dbo.collection("customers").insertOne(myobj, function(err, res) {
    if (err) throw err;
    console.log("1 document inserted");
    db.close();
  });
}); 
console.log("bye");

what exactly i am missing here, or there is issue with my system?

this below a very simple example of callback from chatgpt works

const fs = require('fs');

// Function to read a file asynchronously and invoke a callback when done
function readFileAsync(filePath, callback) {
  fs.readFile(filePath, 'utf8', (err, data) => {
    if (err) {
      callback(err, null); // Pass the error to the callback
    } else {
      callback(null, data); // Pass the data to the callback
    }
  });
}

// Example usage of the readFileAsync function
const filePath = 'example.txt';

readFileAsync(filePath, (err, data) => {
  if (err) {
    console.error('Error reading the file:', err);
  } else {
    console.log('File content:', data);
  }
});

why inbuilt callbacks not working?