It really doesn't matter that you are allowed to drive 125cc motorbikes in Spain, unless you can get that drivers license "translated" into an international driving permit.

I would not recommend renting a scooter or motorbike in Thailand without a valid international driving permit for the type of vehicle you intend to drive, as I'm pretty sure any sensible insurance company will not pay you anything if you have an accident. Just look at the number of rookie tourists who have motorbike accidents in Thailand and end up having to resort to crowdfunding to try and pay their hospital bills. And those are the lucky ones, at least they're still alive...

I agree with Nick that it's safer to rent a car - not to mention more comfortable when it starts raining. Note that you still need an international driving permit though! The downsides to a car compared to a scooter is of course that it's a bit more expensive (but still cheap compared to the rest of the world), it will often take you longer to drive (can't pass between cars) and you'll have a harder time finding parking sometimes.

Finally, I would recommend anyone who wants to travel in Asia or anywhere else by motorbike, to do the only sensible thing - do the training to get a valid motorbike license in your home country (and get it translated into an international driving permit). Also, avoid leaving your passport as deposit - it's not only illegal to hand over your passport, it's also a huge risk. Shop around for a place where you can leave a copy of your passport and/or cash. And shoot a detailed video of the bike when picking it up, detailing every tiny scratch and other damages. That way you'll be in a much better position should the renter claim that you damaged the vehicle when returning it.

It really doesn't matter that you are allowed to drive 125cc motorbikes in Spain, unless you can get that drivers license "translated" into an international driving permit. Also, while 30 minutes of practice in a parking lot is better than nothing, it really doesn't give you the experience that you would have if you take a motorbike driving course. Things such as braking technique, steering in low vs. high speed, countersteering, risk awareness, vehicle safety inspection, etc. etc.

I would not recommend renting a scooter or motorbike in Thailand without a valid international driving permit for the type of vehicle you intend to drive, as I'm pretty sure any sensible insurance company will not pay you anything if you have an accident. Just look at the number of rookie tourists who have motorbike accidents in Thailand and end up having to resort to crowdfunding to try and pay their hospital bills. And those are the lucky ones, at least they're still alive...

I agree with Nick that it's safer to rent a car - not to mention more comfortable when it starts raining. Note that you still need an international driving permit though! The downsides to a car compared to a scooter is of course that it's a bit more expensive (but still cheap compared to the rest of the world), it will often take you longer to drive (can't pass between cars) and you'll have a harder time finding parking sometimes.

Finally, I would recommend anyone who wants to travel in Asia or anywhere else by motorbike, to do the only sensible thing - do the training to get a valid motorbike license in your home country (and get it translated into an international driving permit). Also, avoid leaving your passport as deposit - it's not only illegal to hand over your passport, it's also a huge risk. Shop around for a place where you can leave a copy of your passport and/or cash. And shoot a detailed video of the bike when picking it up, detailing every tiny scratch and other damages. That way you'll be in a much better position should the renter claim that you damaged the vehicle when returning it.